JP6043606B2 - Magnetic element control device, magnetic element control method, and magnetic detection device - Google Patents

Description

  The present invention relates to a signal processing circuit and a physical quantity measuring apparatus using the circuit, and in particular, a magnetic element control device for driving a time-resolved fluxgate (hereinafter referred to as FG) magnetic element, and a magnetic element control. The present invention relates to a method and a magnetic detection device that detects a magnetic field using the method.

In general, FG magnetic elements have higher sensitivity to detect magnetic fields than other magnetic elements such as Hall elements and magnetoresistive elements, and can be reduced in size. It is used for.
FIG. 14 is a diagram illustrating a configuration example of a time-resolved FG type magnetic element (magnetic field proportional measurement). In FIG. 14, in the FG magnetic element, an excitation winding and a detection winding are wound around the outer peripheral surface of a magnetic core made of a high permeability material. The region around which the excitation winding is wound functions as an excitation coil driven by the excitation signal, and the region around which the detection winding is wound functions as a detection coil that outputs a detection signal. The stationary magnetic field Hex is a magnetic field penetrating through a cylindrical space formed by the excitation winding and the detection winding of the magnetic core.

  FIG. 15 is a waveform diagram illustrating the principle of magnetic detection in a magnetic field proportional type using a time-resolved FG type magnetic element. Here, FIG. 15A is a diagram showing the excitation current supplied to the excitation coil of the magnetic element, where the vertical axis shows the current value of the excitation current and the horizontal axis shows the time. FIG. 15B is a diagram showing the magnetic flux density of the magnetic field generated in the magnetic core by the exciting coil of the magnetic element, the vertical axis showing the magnetic flux density in the magnetic core, and the horizontal axis showing the time. Yes. FIG. 15C is a diagram showing the voltage value of the pulse generated by the induced electromotive force in the detection coil of the magnetic element, the vertical axis shows the voltage value of the pickup voltage of the detection coil, and the horizontal axis shows the time. Yes.

In FIG. 15, in order to drive the excitation coil, a signal of excitation current Id alternating between terminals of the excitation coil (hereinafter referred to as excitation signal), that is, a triangular wave shape as shown in FIG. The excitation signal (that is, the triangular wave current signal) is applied (see, for example, Patent Document 3).
Thus, in the case of FIG. 15C in the time when the direction of the excitation current changes (positive and negative alternating time zone of the excitation current), at time t1 and time t2, the detection coil has positive and negative pulses due to the induced electromotive force. (Pickup signal, ie, pu signal) is generated. Hereinafter, the voltage Vp (pickup voltage) of this pulse is used as a detection signal. This detection signal is generated between the terminals of the detection coil as a pulse having a positive and negative polarity voltage continuously corresponding to the period of the triangular wave current signal (see, for example, Patent Document 1 and Patent Document 2).

When a stationary magnetic field Hex (see FIG. 14) penetrating through the cylindrical space formed by the excitation winding and the detection winding of the magnetic core is applied to this magnetic element, the stationary current corresponding to this stationary magnetic field Hex in the excitation winding. Flows. That is, the above-described steady current is superimposed as an offset on the excitation current Id of the excitation signal applied to the excitation winding.
As a result, the driving state of the exciting coil changes due to the alternating excitation signal due to this offset, that is, the time when the direction in which the exciting current Id flows changes when the stationary magnetic field Hex is applied and when the stationary magnetic field Hex is It varies depending on whether it is not applied.

  At this time, as shown in FIG. 15C, the stationary magnetic field Hex is applied in the same direction as the magnetic field generated by the exciting coil as compared with the case where the stationary magnetic field Hex is not applied (Hex = 0). In the case of (Hex> 0), the time t1, which is the timing at which the direction in which the excitation current Id flows, is delayed, and the time t2 is advanced (time Tm is shorter than T / 2). On the other hand, when the stationary magnetic field Hex in the direction opposite to the magnetic field generated by the exciting coil is applied (Hex <0), the direction in which the exciting current Id flows changes as compared with the case where the stationary magnetic field Hex is not applied. At the timing, the time t1 becomes earlier and the time t2 becomes later (time Tp becomes longer than T / 2).

As a result, the change in the magnetic flux density φ in the magnetic core, which changes according to the timing at which the direction in which the excitation current Id flows, also changes corresponding to the steady current due to the steady magnetic field Hex superimposed on the excitation current Id. It will be.
When the direction of the magnetic flux changes, an induced electromotive force is generated in a direction that cancels the change of the magnetic flux with respect to the detection coil. Occur. On the other hand, the detection signal is generated as a positive voltage pulse at the timing when the excitation current Id changes from negative to positive.

Therefore, the FG type magnetic element compares the timing at which the detection signal is output when the stationary magnetic field Hex is not applied with the timing at which the detection signal is output when the stationary magnetic field Hex is applied. Thus, the magnitude of the stationary magnetic field Hex can be indirectly measured. That is, when a steady magnetic field Hex is applied, a specific steady current flows in the drive coil, so that a constant offset is superimposed on the excitation signal, and the time interval between the negative and positive voltage pulse detection signals changes.
Therefore, the magnetic detection device using the FG type magnetic element measures the intensity of the stationary magnetic field Hex applied from the outside by measuring the time interval at which the negative and positive voltage pulse detection signals are generated. (For example, refer to Patent Document 1, Patent Document 2, and Patent Document 3).

Here, the maximum value of the excitation current Id applied to the excitation coil is set to a value that generates a magnetic field that is equal to or higher than the saturation magnetic flux density of the magnetic core. Thereby, the measurement magnetic field range of the magnetic element includes a time of one period of the excitation signal and a time change (hereinafter referred to as excitation efficiency) corresponding to the current value of the steady current as an offset by applying the steady magnetic field Hex. Determined from.
That is, as shown in FIG. 15, the period from time t0 to time t3 is one period of the excitation signal, and this period width is time T. When the stationary magnetic field Hex is not applied (Hex = 0), a positive voltage detection signal (hereinafter referred to as second detection) from time t1 when a negative voltage detection signal (hereinafter referred to as first detection signal) is output. The time Tw until the time t2 when the signal is detected is a half cycle of the excitation signal, and thus becomes the time T / 2.

  In addition, when a stationary magnetic field Hex is applied, a time width (hereinafter referred to as a measurement time width) from when the first detection signal is output until the second detection signal is detected changes with respect to time T / 2. To do. Here, as shown in FIG. 14, when the magnetic flux direction of the stationary magnetic field Hex is a solid arrow (Hex> 0), the time width Tm is determined from the time T / 2 because the direction is the same as the magnetic flux direction generated by the exciting coil. On the other hand, when the magnetic flux direction of the stationary magnetic field Hex is a dashed arrow (Hex <0), the time width Tp is the time T / 2 because the direction is opposite to the magnetic flux direction generated by the exciting coil. It becomes longer (Tp> T0). Here, T0 = T / 2.

Next, FIG. 16 is a schematic block diagram illustrating a configuration example of a magnetic detection device using a magnetic element control device in magnetic field proportional control using a time-resolved FG type magnetic element. In FIG. 16, a magnetic element 500 is the magnetic element shown in FIG. 14 and includes a detection coil 502 and an excitation coil 501.
The magnetic element control device 400 includes a magnetic element control unit 401, a clock signal generation unit 402, and a clock signal adjustment unit 403.
The clock signal generation unit 402 generates a clock with a period T and outputs it to the clock signal adjustment unit 403.
The clock signal adjustment unit 403 adjusts the signal level of the supplied clock and outputs the adjusted clock to the magnetic element control unit 401.

The magnetic element control unit 401 includes a detection signal amplification unit 4012, a detection signal comparison unit 4013, an output signal generation unit 4015, a data signal conversion unit 4016, an excitation signal adjustment unit 4017, and an excitation signal generation unit 4018.
The excitation signal generation unit 4018 generates, for example, a triangular wave that is an excitation signal illustrated in FIG. 16A from the clock supplied from the clock signal adjustment unit 403.
The excitation signal adjustment unit 4017 adjusts the voltage level of the excitation signal supplied from the excitation signal generation unit 4018 and supplies it to the excitation coil 501 as an excitation signal.

The exciting coil 501 generates a magnetic field corresponding to the triangular wave in the magnetic core of the magnetic element 500.
The detection coil 502 generates a pulse during positive and negative alternating time zones of the excitation signal in the magnetic core.
The detection signal amplification unit 4012 amplifies the voltage level of the pulse supplied from the detection coil 502 and outputs the amplified voltage level to the detection signal comparison unit 4013 as a detection signal.
The detection signal comparison unit 4013 obtains the difference between the time width of the pulse (detection signal) between the time t1 and the time t2 and T / 2, and outputs this difference to the output signal generation unit 4015.

The output signal generation unit 4015 obtains voltage information corresponding to the difference from the difference indicating the supplied time. The output signal generation unit 4015 outputs the obtained voltage information to the data signal conversion unit 4016.
The data signal conversion unit 4016 reads the magnetic field intensity corresponding to the voltage value of the voltage information from the voltage value magnetic field table previously written and stored in the internal storage unit, and the intensity of the magnetic field applied to the magnetic element 500 Ask for. The voltage value magnetic field table is a table showing the correspondence between the voltage value of the voltage information and the intensity of the applied stationary magnetic field Hex. A magnetic field intensity detection device (not shown) is connected to the data signal output terminal.

  Next, FIG. 17 is a diagram illustrating a configuration example of a time-resolved FG type magnetic element (magnetic field balance type measurement). As shown in FIG. 17, the magnetic element of the FG method in the magnetic field balance measurement is different from the magnetic element of FIG. 14 in that the excitation winding and the detection winding are provided on the outer peripheral surface of the magnetic core made of a high permeability material. In addition to the wire, a feedback (hereinafter FB) winding is wound. The region where the excitation winding is wound functions as an excitation coil driven by the excitation signal, and the region where the detection winding is wound functions as a detection coil which outputs the detection signal, and the feedback winding is wound. The functioning area functions as an FB coil driven by a feedback signal. The stationary magnetic field Hex is a magnetic field penetrating through a cylindrical space formed by the excitation winding and the detection winding of the magnetic core.

Next, FIG. 18 is a waveform diagram illustrating the principle of magnetic detection in magnetic field balance type measurement using a time-resolved FG type magnetic element.
FIG. 18A shows the excitation current supplied to the excitation coil of the magnetic element, the vertical axis shows the current value of the excitation current, and the horizontal axis shows time. The exciting current is a positive / negative alternating signal with a reference current value of 0 A (zero ampere) as a boundary. FIG. 18B is a diagram illustrating an FB signal (that is, a feedback signal) that is a current applied to the FB coil of the magnetic element, where the vertical axis indicates the current value of the FB signal, and the horizontal axis indicates time. . FIG. 18C is a diagram showing the voltage value of a pulse generated by the induced electromotive force in the detection coil of the magnetic element, the vertical axis shows the voltage value of the pickup signal, and the horizontal axis shows time.

As shown in FIG. 18, in the case of magnetic field balance type measurement, a magnetic field that cancels out the stationary magnetic field Hex (stationary magnetic field passing through the magnetic core) applied to the magnetic element is generated by the FB coil. Then, the stationary magnetic field Hex applied to the magnetic element is measured from the current value when the FB coil generates a magnetic field that cancels the stationary magnetic field.
In the magnetic field balance type, in addition to the excitation coil and the detection coil, the FB coil is provided in the magnetic element as a coil for generating a magnetic field for canceling the stationary magnetic field in the magnetic core.
Hereinafter, in the present specification, the FB coil FB control is a method in which the FB signal is applied to cancel the stationary magnetic field in the magnetic core and measure the magnetic field.

In the case of magnetic field balance type measurement, the time interval of pulses generated in the detection coil is measured in the positive and negative alternating time zones of the excitation signal applied to the excitation coil, as in the magnetic field proportional expression already described. Then, based on the measurement result, the time from the time t1 when the negative voltage detection signal is output to the time t2 when the positive voltage detection signal is detected is T / 2, so that the time is T / 2. Apply FB signal.
For example, in FIG. 18C, when the time width between time t1 and time t2 becomes wider than T / 2, a stationary magnetic field Hex in the negative direction is applied as shown in FIG. This means that the waveform of the excitation signal has changed from the waveform L0 to the waveform L2. For this reason, in order to return the waveform L2 of the excitation signal to the position of the curve L0 where the time width between the time t1 and the time t2 is T / 2, the FB coil is represented by the waveform FB2 in FIG. An FB signal having a current value is applied.

On the other hand, in FIG. 18C, when the time width between the time t1 and the time t2 becomes narrower than T / 2, a stationary magnetic field Hex in the positive direction is applied as shown in FIG. This means that the waveform of the excitation signal has changed from the waveform L0 to the waveform L1. Therefore, in order to return the waveform L1 of the excitation signal to the position of the waveform L0, an FB signal having a current value represented by the waveform FB1 in FIG. 18B is applied to the FB coil.
Then, the strength of the stationary magnetic field applied to the magnetic element is obtained from the current value of the FB signal applied to the FB coil so that the time width between time t1 and time t2 is T / 2.

Next, FIG. 19 is a block diagram showing a configuration example of a magnetic detection device using a magnetic element control device in FB coil FB control. In FIG. 19, the magnetic element 300 includes an excitation coil 301, an FB coil 302, and a detection coil 303.
The magnetic element control device 200 includes a magnetic element control unit 201, a clock signal generation unit 202, and a clock signal adjustment unit 203.
The clock signal generation unit 202 generates a clock with a period T and outputs it to the clock signal adjustment unit 203.
The clock signal adjustment unit 203 adjusts the signal level of the supplied clock and outputs the adjusted clock to the magnetic element control unit 201.

The magnetic element control unit 201 includes a detection signal amplification unit 2012, a detection signal comparison unit 2013, a feedback signal adjustment unit 2014, a feedback signal conversion unit 2015, a data signal conversion unit 2016, an excitation signal adjustment unit 2017, and an excitation signal generation unit 2018. ing.
The excitation signal generation unit 2018 generates, for example, a triangular wave that is an excitation signal shown in FIG. 18A from the clock supplied from the clock signal adjustment unit 203.
The excitation signal adjustment unit 2017 adjusts the voltage level of the excitation signal supplied from the excitation signal generation unit 2018 and supplies it to the excitation coil 301 as an excitation signal.

The exciting coil 301 generates a magnetic field corresponding to the triangular wave in the magnetic core of the magnetic element 300.
The detection coil 303 generates a pulse during positive and negative alternating time zones of the excitation signal in the magnetic core.
The FB coil 302 generates a magnetic field that cancels the stationary magnetic field Hex applied to the magnetic core of the magnetic element 300 in accordance with the supplied FB signal.
The detection signal amplification unit 2012 amplifies the voltage level of the pulse supplied from the detection coil 303 and outputs the amplified voltage level to the detection signal comparison unit 2013 as a detection signal.
The detection signal comparison unit 2013 obtains the difference between the time width between the time t1 and the time t2 of the pulse (detection signal) and T / 2, and outputs this difference to the feedback signal conversion unit 2015.
The feedback signal conversion unit 2015 obtains the current value of the FB signal supplied to the FB coil 302 from the obtained difference.

Here, the feedback signal conversion unit 2015 reads the current value corresponding to the obtained difference from the FB current value table previously written and stored in the internal storage unit, and obtains the current value of the FB signal. The FB current value table is a table showing the correspondence between the difference and the current value (digital value) that cancels the stationary magnetic field in the magnetic core.
The feedback signal adjustment unit 2014 performs D / A (Digital / Analog) conversion on the current value of the FB signal supplied from the feedback signal conversion unit 2015, and the generated current as the FB signal is supplied to the FB coil 302. Output. Further, the feedback signal adjustment unit 2014 outputs the current value of the FB signal supplied from the feedback signal conversion unit 2015 to the data signal conversion unit 2016.

  The data signal conversion unit 2016 obtains the strength of the stationary magnetic field canceled in the magnetic core, that is, the strength of the stationary magnetic field Hex applied to the magnetic element 300 from the current value of the supplied FB signal. Here, the data signal conversion unit 2016 reads out the magnetic field intensity corresponding to the current value of the FB signal from the current value magnetic field table previously written and stored in the internal storage unit, and is applied to the magnetic element 300. Find the strength of the magnetic field. The current value magnetic field table is a table showing the correspondence between the current value of the FB signal and the strength of the applied stationary magnetic field Hex. A magnetic field intensity detection device (not shown) is connected to the data signal output terminal.

When performing magnetic detection in the magnetic field proportional type using the above-described time-resolved FG type magnetic element, the amount of magnetic field generated per current applied to the coil due to the material and structure of the magnetic core of the magnetic element 300 (hereinafter referred to as the magnetic field) And the excitation efficiency) and the intensity of the excitation signal determine the measurable magnetic field range.
On the other hand, when magnetic detection in a magnetic field balance type is performed using a time-resolved FG type magnetic element, detection is performed at a constant time interval (T / 2) regardless of the stationary magnetic field Hex applied to the magnetic element 300. The magnetic field near the magnetic core is maintained in an equilibrium state so that a signal is output. For this reason, the magnetic field can be measured within a range that is limited by the power supply voltage of the entire magnetic element 300, that is, the current value of the FB signal can be supplied.

In addition, when performing magnetic detection in the magnetic field proportional type using a time-resolved FG type magnetic element, the time interval at which the detection signal is output changes according to the magnetic field, so that the linearity of the magnetic sensitivity is It will be reflected directly in the characteristics.
On the other hand, when performing magnetic detection in a magnetic field balance type using a time-resolved FG type magnetic element, the magnetic field dependence of excitation efficiency is small as a characteristic of the magnetic element, so that the detection signal waveform and the detection signal are generated. The continuity of the time interval is easily maintained.
Therefore, for example, when applied to a magnetic element that measures a magnetic field generated by a current of about several hundreds A (ampere) at maximum while maintaining linearity in the entire measurement current range, conventionally, compared to a magnetic field proportional expression, Magnetic detection in a magnetic field balance type is mainly used.

JP 2008-292325 A JP 2007-078423 A JP 2007-078422 A

When magnetic detection is performed by the magnetic field proportional method using the above-described time-resolved FG type magnetic element, the measurable magnetic field range is limited by the excitation efficiency and the excitation signal of the magnetic element 300 as described above.
For this reason, when a magnetic field proportional magnetic element is applied as a current sensor having a maximum measurement current of about several hundred A, in addition to the dependence of the linearity of the output of the single magnetic element on the strength of the magnetic field, the magnetic element is driven. There is a problem that the measurement range of the magnetic field that can obtain high-accuracy output linearity is limited by the limitation of the power supply voltage and the allowable maximum current value.

  Further, when the waveform of the detection signal generated by the detection coil changes depending on the strength of the stationary magnetic field Hex and the temperature of the magnetic core, the time differential value of the rise of the detection signal waveform and the output fluctuation of the detection signal There is a correlation. For this reason, the time fluctuation value of the output of the detection signal changes depending on the strength of the magnetic field, so that in the measurement of the magnetic field strength, the time fluctuation value increases, particularly as the magnetic field strength increases. The magnetic field cannot be detected.

On the other hand, when magnetic detection is performed by a magnetic field balance type using a time-resolved FG type magnetic element, the FB signal is generally performed by current control in the FB coil FB control.
As described above, the current value in the FB control signal and the intensity of the magnetic field generated by this current value are proportional to each other, and the temperature dependence of the magnetic sensitivity is theoretically determined by using the excitation signal as the current control. Does not occur. Therefore, there is an advantage that temperature compensation of magnetic sensitivity is unnecessary. However, even when the excitation signal is performed by current control, a method of generating an excitation triangular wave once by voltage control is generally used. For this reason, it is necessary to generate an excitation triangular wave of a current used for current control by using a voltage-current conversion circuit for the excitation triangular wave of the voltage generated by voltage control. As a result, there is a problem that the temperature change of the output value of the magnetic sensor occurs in a constant magnetic field environment depending on the temperature dependency of the offset value of the amplifier used in the voltage-current conversion circuit.

As described above, depending on the type of magnetic element control method, there are advantages and disadvantages with respect to linearity of magnetic sensitivity and current consumption. However, the characteristics relating to the temperature dependence of the offset and the temperature dependence of the magnetic sensitivity to the control method of the excitation triangular wave applied to the excitation coil are common. For this reason, the current dependency of the excitation signal reduces the temperature dependence of the magnetic sensitivity, but the temperature dependence of the output value occurs. On the other hand, when the excitation signal is voltage controlled, the temperature dependence of the output value is reduced, but the temperature dependence of the magnetic sensitivity occurs.
Therefore, it is difficult to reduce both the temperature dependency of the magnetic sensitivity and the temperature dependency of the output value at the same time, regardless of whether the excitation triangular wave is performed by voltage control or current control.

  The magnetic balance type measurement magnetic field range is not limited by the excitation efficiency and excitation current of the magnetic element, and the measurement magnetic field range is limited by the appropriate power supply voltage and the allowable maximum FB current value of the entire magnetic element. Further, by controlling the current of the FB signal, even if the coil temperature of the feedback coil changes due to the difference in the current amount of the feedback signal and the resistance value of the coil fluctuates, it is controlled with a constant current. For this reason, even in a high magnetic field environment where the amount of change in the FB signal is large, linearity with high magnetic sensitivity can be maintained.

  In addition, when the excitation efficiency of each of the excitation coil and the feedback coil changes due to individual deviations in the characteristics of the magnetic elements, the FB convergence time in magnetic equilibrium changes. However, it is possible to suppress the occurrence of the FB convergence residual by optimizing the design of the control circuit that controls the period coil. In particular, in the FB coil FB control, when the ratio between the excitation efficiency of the excitation coil and the excitation efficiency of the feedback coil is kept constant, the ratio of the magnetic sensitivity between the excitation coil and the feedback coil does not change. Will not change.

Therefore, when the exciting coil and the feedback coil are formed simultaneously by a semiconductor process or the like, even if the coil resistance changes, the ratio of the coil resistance is easily maintained. The convergence time does not change.
On the other hand, since an FB signal having a current proportional to the magnetic field is required, current consumption in the feedback coil control circuit is increased as compared with the magnetic proportional type. Furthermore, when the FB signal is current controlled, a constant current is generated, so that it is necessary to introduce a voltage-current conversion circuit, and there is a problem that current consumption of the entire control circuit increases.

  Further, when the FB signal is current controlled, there is a problem that the reference potential of the differential signal in one control circuit is likely to fluctuate with time as the amount of feedback current increases and become unstable. In addition, when the excitation vibration is current control, the temperature dependence of the magnetic sensor in a constant magnetic field environment occurs due to the temperature dependence of the offset in the amplifier of the voltage-current converter circuit, as well as the characteristics of the excitation signal in the magnetic proportional type. There is a problem to do.

As described above, depending on the type of control method, there are advantages and disadvantages of each control method with respect to linearity of magnetic sensitivity and current consumption.
However, the characteristics relating to the temperature dependence of the offset and the temperature dependence of the magnetic sensitivity with respect to the control method of the triangular wave signal for driving the exciting coil have in common regardless of the type of the control method.
That is, when the excitation signal for the excitation coil is current control, the temperature dependence of the magnetic sensitivity is suppressed, but the temperature dependence of the output value of the magnetic element occurs. On the other hand, when the excitation signal is voltage controlled, the temperature dependence of the output value of the magnetic element can be reduced, but the temperature dependence of the magnetic sensitivity occurs.
Therefore, even if the excitation coil control method is changed, it is difficult to simultaneously reduce both the temperature dependence of the magnetic sensitivity and the temperature dependence of the output value of the magnetic element.

  The present invention has been made in view of such circumstances, and suppresses both the temperature dependence of the magnetic sensitivity and the temperature dependence of the output value of the magnetic element at the same time without depending on the control method of the exciting coil. It is an object of the present invention to provide a magnetic element control device, a magnetic element control method, and a magnetic detection device that are capable of performing the above.

The present invention has been made to solve the above-described problems, and the magnetic element control device of the present invention applies an alternating signal to a plurality of exciting coils provided in a magnetic core, and applies the alternating signal to the magnetic core. From the provided detection coil, the waveform of the pulse signal with different polarity detected corresponding to the alternating signal is detected, and the magnetic element for detecting the stationary magnetic field is controlled by the detection interval of the pulse signal with different polarity. A first excitation signal generation unit that generates a first alternating signal in the alternating signal , which is an excitation signal that is current-controlled excitation that is applied to the first excitation coil among the excitation coils. winding direction of the first exciting coil and the winding is applied to the second excitation coil is opposite of said excitation coil, a excitation signal current control, the first alternating signal in the alternating signal A second excitation signal generator for generating a second alternating signal having different polarities in synchronization, and a detection signal for detecting a positive or negative voltage detection signal generated by an induced electromotive force when the current direction of the alternating signal is switched and a comparison unit, the polarity of the change in the offset in each of the first excitation signal generator and the second excitation signal generating section is characterized by reverse der Rukoto in positive and negative temperature characteristics.

  The magnetic element control device of the present invention is characterized in that the second excitation signal generation unit includes a circuit for inverting the polarity of signal change with respect to a reference potential in the first excitation signal generation unit.

  The magnetic element control device of the present invention includes an output signal generation unit that converts a time width between detection signals of positive voltage and negative voltage into voltage information, and data signal conversion that outputs the voltage information as a data signal indicating magnetic field strength And a section.

A magnetic element control device according to the present invention cancels a stationary magnetic field applied to the magnetic element from the voltage information, and a feedback signal generation unit that converts a time width between detection signals of a positive voltage and a negative voltage into voltage information. for generating a magnetic field to the feedback coil, the feedback signal adjusting unit for generating a feedback signal applied to the feedback coil, the feedback signal further comprise a data signal converting unit that outputs a data signal indicating a magnetic field strength It is characterized by.

  In the magnetic element control device according to the present invention, each of the first excitation signal generation unit and the second excitation signal generation unit performs excitation in which the feedback signal is superimposed on each of the first alternating signal and the second alternating signal. A signal generation circuit is provided.

According to the magnetic element control method of the present invention, an alternating signal is applied to a plurality of exciting coils provided in the magnetic core, and detected from the detection coil provided in the magnetic core corresponding to the alternating signal. A magnetic element control method for detecting a waveform of a pulsed signal having a different polarity and controlling a magnetic element for detecting a stationary magnetic field based on a detection interval of the pulsed signal having a different polarity. A first excitation signal generation process for generating a first alternating signal in the alternating signal , which is an excitation signal subjected to current control applied to the coil, and a winding direction of the first excitation coil and the winding of the excitation coil There is applied to the second excitation coil is reversed, it is the excitation signal current control, a second excitation for generating different second alternating signal polarity synchronized with the first alternating signal in the alternating signal A signal generating process, the current direction of the alternating signal and a detection signal comparison step of detecting a detection signal of a positive or negative voltage generated by the induced electromotive force when Ru switch, said first excitation signal generation process and said second the polarity of the change of the offset in each of the 2 excitation signal generation process and said inverse der Rukoto in positive and negative temperature characteristics.

The magnetic detection device of the present invention is a magnetic detection device for detecting the intensity of an applied stationary magnetic field, and generates an alternating signal with a fluxgate type magnetic element comprising a first excitation coil, a second excitation coil, and a detection coil. An excitation signal generating unit for generating, a first excitation signal generating unit for generating a first alternating signal in the alternating signal , which is a current-controlled excitation signal applied to the first excitation coil, and the first excitation coil And a second alternating signal having a polarity that is synchronized with the first alternating signal in the alternating signal , which is an excitation signal subjected to current control , applied to a second exciting coil having a winding direction opposite to that of the winding. second and excitation signal generation unit, a detection signal comparator which detects a detection signal of a positive or negative voltage current direction of the alternating signal is generated in the induced electromotive force when Ru switch, positive or negative voltage the detection signal of the Interval Based, and a data signal converter which outputs a data signal indicating a magnetic field strength, the polarity of the change in the offset in each of the first excitation signal generator and the second excitation signal generating unit is positive and negative temperature characteristics and wherein the Gyakudea Rukoto.

The present invention includes a first excitation signal generation unit, a second excitation signal generation unit in which the polarity of an alternating signal generated with the first excitation signal generation unit is inverted, and the sign of the temperature coefficient in the change of the offset amount is inverted. , A first alternating signal and a second alternating signal are generated, respectively. Then, the first alternating signal is applied to the first exciting coil, and the second alternating signal is applied to the second exciting coil whose winding direction is opposite to that of the first exciting coil.
Thus, according to the present invention, the temperature dependence of the magnetic sensitivity is suppressed by current control, and the offset change polarity in each of the first excitation signal generation unit and the second excitation signal generation unit is positive and negative. Since the characteristics are opposite, mutual offsets can be canceled and the temperature dependence of the output value of the magnetic element is suppressed. Therefore, according to the present invention, it is not necessary to provide a temperature compensation circuit for compensating for the temperature characteristic of the offset, and the temperature dependence of the magnetic sensitivity and the output value of the magnetic element can be controlled without depending on the excitation coil control method. Both temperature dependence can be suppressed simultaneously.

1 is a schematic block diagram illustrating a configuration of a magnetic detection device including a magnetic element control device 10 and a magnetic element 50 according to a first embodiment of the present invention. It is a figure which shows the structural example of the excitation signal adjustment part 116 and the excitation signal production | generation part 117 in FIG. It is a figure which shows the structural example of the magnetic element 50 which is a fluxgate (FG) type | mold magnetic element of the magnetic element 50 in this embodiment. It is a figure which shows the temperature dependence of the offset in each zero magnetic field of the 1st excitation coil 51 and the 2nd excitation coil 52. FIG. It is a flowchart explaining the operation example of the magnetic element control process of the magnetic element control apparatus 10 by this embodiment. It is a figure explaining the structure of the magnetic detection apparatus which consists of the magnetic element control apparatus 20 and the magnetic element 50 by the 2nd Embodiment of this invention. It is a graph which shows the principle of operation of a fluxgate type magnetic element. 7 is a diagram illustrating a configuration example of a feedback signal adjustment unit 214, an excitation signal adjustment unit 216, and an excitation signal generation unit 217 in FIG. 7 is a diagram illustrating another configuration example of the feedback signal adjustment unit 214, the excitation signal adjustment unit 216, and the excitation signal generation unit 217 in FIG. It is a flowchart which shows the operation example of the magnetic element control apparatus 20 in 2nd Embodiment. It is a figure explaining the structure of the magnetic detection apparatus which consists of the magnetic element control apparatus 30 and the magnetic element 50 by the 3rd Embodiment of this invention. It is a flowchart explaining the operation example of the magnetic element control process (Generation process of the feedback voltage by a digital value) which the magnetic element control apparatus 30 in 3rd Embodiment performs. It is a flowchart explaining the operation example of the magnetic element control process (Generation process of the feedback voltage by an analog value) which the magnetic element control apparatus 130 in 3rd Embodiment performs. It is a figure which shows the structural example of the magnetic element (magnetic field proportional measurement) of a time-resolved FG system. It is a wave form diagram explaining the principle of the magnetic detection in a magnetic field proportional type using a time-resolved FG type magnetic element. It is a block diagram which shows the structural example of the magnetic detection apparatus using the magnetic element control apparatus in a magnetic field proportional control using a time-resolved FG type magnetic element. It is a figure which shows the structural example of the magnetic element (magnetic field balance type | mold measurement) of a time-resolved FG system. It is a wave form diagram explaining the principle of the magnetic detection in a magnetic field balance type | mold measurement using a time-resolved FG type magnetic element. It is a block diagram which shows the structural example of the magnetic detection apparatus using the magnetic element control apparatus in FB coil FB control.

<First Embodiment>
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. The present embodiment is a magnetic control device that performs a magnetic proportional magnetic detection process using an FG magnetic element. FIG. 1 is a diagram for explaining a configuration of a magnetic detection device including a magnetic element control device 10 and a magnetic element 50 according to the first embodiment of the present invention. The magnetic element control device 10 includes a magnetic element control unit 11, a clock signal generation unit 102, a clock signal adjustment unit 103, and a data signal determination unit 104.

The magnetic element control apparatus 10 according to the present embodiment uses a time-resolved magnetic field to determine the strength of a steady magnetic field applied to a fluxgate magnetic element 50 including a first excitation coil 51, a second excitation coil 52, and a detection coil 53. When detecting by the proportional expression, each of the first excitation signal DR1 (first alternating signal) and the second excitation signal DR2 (second alternating signal) applied to each of the first excitation coil 51 and the second excitation coil 52. To control.
The magnetic element control unit 11 includes a detection signal amplification unit 111, a detection signal comparison unit 112, a time-output signal conversion unit 113, a data signal conversion unit 115, an excitation signal adjustment unit 116, and an excitation signal generation unit 117.

The clock signal generation unit 102 includes an oscillator that generates a clock signal having a predetermined period, and outputs the generated clock signal to the clock signal adjustment unit 103.
The clock signal adjustment unit 103 performs processing such as amplifying the signal level of the supplied clock signal or changing the cycle of the clock signal, and outputs the processing result clock signal to the excitation signal generation unit 117.

  The data signal determination unit 104 determines whether or not the voltage value of the data signal indicating the strength of magnetism supplied from the data signal conversion unit 115 (detailed later) is included in a preset data range (output data designation range). Judgment is made. In the data signal determination unit 104, the data range is previously written and stored in an internal storage unit. In this data range, whether or not the voltage value indicated by the data signal amplified and output by the data signal conversion unit 115 is included in a region where the magnetic field strength of the magnetic field and the voltage value indicating the magnetic field strength are in a linear relationship. This is a voltage value range for determining whether or not.

  Here, when the voltage value of the data signal is not included in the data range in which the magnetic field strength and the voltage value are in a linear relationship, the data signal determination unit 104 displays an error signal that is a data signal indicating an error as an external magnetic field. Output to the intensity detector. In addition, when the voltage value of the data signal is included in the data range, the data signal determination unit 104 outputs a data signal indicating the voltage value to the external magnetic field strength detection device via the data signal output terminal. .

In the magnetic element control unit 11, the detection signal amplification unit 111 amplifies the voltage at both ends of the detection coil 53 of the magnetic element 50 with a preset amplification degree, and outputs the amplified signal to the detection signal comparison unit 112 as a detection signal.
The detection signal comparison unit 112 obtains the difference between the time width between the time t1 (first detection signal) and the time t2 (second detection signal) at which the detection signals having different polarities are output, and T / 2, and calculates the difference. A sequence of pulses having a duty ratio corresponding to (a sequence of pulses transmitted in a time series at a constant period) is output to the time-output signal conversion unit 113.

The time-output signal conversion unit 113 converts the pulse train having the duty ratio supplied from the detection signal comparison unit 112 into a DC voltage using a PWM circuit or the like to obtain a measurement voltage, and this measurement voltage is supplied to the data signal conversion unit 115. Output.
The data signal conversion unit 115 subtracts the offset voltage in the zero magnetic field measured in advance from the measurement voltage, amplifies the data with a predetermined amplification factor, and outputs the data signal to the data signal determination unit 104.

Based on the clock signal supplied from the clock signal adjustment unit 103, the excitation signal generation unit 117 generates an alternating signal, for example, a triangular wave signal as an alternating voltage signal that alternates with 0 V as a reference potential.
The excitation signal adjustment unit 116 amplifies the triangular wave signal generated by the excitation signal generation unit 117 at a predetermined amplification factor, generates a first excitation signal DR1 that is a triangular wave current signal, and applies the first excitation signal DR1 to the first excitation coil 51. To do.
Similarly, the excitation signal adjustment unit 116 applies the second excitation signal DR2, which is an inverted triangular wave current signal obtained by inverting the triangular wave current signal (ie, shifting the phase by 180 degrees), to the second excitation coil 52. To do.

Next, FIG. 2 is a diagram illustrating a configuration example of the excitation signal adjustment unit 116 and the excitation signal generation unit 117 in FIG. In FIG. 2, the excitation signal adjustment unit 116 includes a differential amplifier 2001 (first excitation signal generation unit), a differential amplifier 2002 (second excitation signal generation unit), an inverter 2003, and a resistor 2004. Here, the resistance value of the resistor 2004 is the resistance value R. The resistor 2004 is interposed between the output terminal of the excitation signal generator 117 and the (−) terminal (inverting input terminal) of the differential amplifier 2001 and the input terminal of the inverter 2003. The resistor 2004 converts the voltage Vex of the triangular wave excitation signal output from the excitation signal generation unit 117 into a voltage / current, and supplies the converted voltage Vex to the (−) terminal of the operational amplifier 2001.
The inverter 2003 has an output terminal connected to the (−) terminal (inverted input terminal) of the operational amplifier 2002, changes the polarity of the current I (and reverses the flow direction), and supplies the current to the (−) terminal of the operational amplifier 2002. To do. That is, the inverter 2003 applies a negative drive current (−I) having a current absolute value equal to the drive current I and a phase shift of 180 degrees to the (−) terminal of the differential amplifier 2002. . In the case of the excitation voltage Vex, the excitation current Iex that is the drive current I is obtained by the following equation.
Iex = (Vex− (V −)) / R = (Vex−Vref) / R

With the above-described configuration, the excitation signal adjusting unit 116 sends the first excitation signal DR1 having the current value Iex to the first excitation coil 51, and the current value −Iex (to the current value Iex) to the second excitation coil 52. Current signal whose phase is 180 degrees out of phase). The first excitation signal DR1 and the second excitation signal DR2 are triangular wave current signals, but have different current polarities. That is, as the alternating signal, the first excitation signal DR1 and the second excitation signal DR2 are waveforms in which the absolute value of the amplitude of the current value is equal and the phases are shifted from each other by 180 degrees.
Further, each of the differential amplifier 2001 and the differential amplifier 2002 is supplied with the driving current I, the voltage Vref is set as a reference potential, and the first excitation signal DR1 (current value Iex) is supplied to the first excitation coil 51. In addition, the second excitation signal DR2 (current value − (− Iex)) is supplied to the second excitation coil 52.

  The differential amplifier 2001 and the differential amplifier 2003 use a configuration in which the temperature dependency of the offset is different, that is, a configuration having a characteristic in which the temperature dependency of the offset is opposite. For example, the differential amplifier 2001 is created with a circuit configuration in which an offset of a current value output corresponding to a rise in temperature increases. On the other hand, the differential amplifier 2002 is formed with a circuit configuration in which an offset of a current value output corresponding to a rise in temperature decreases. In this case, the offset amplifier 2001 and the differential amplifier 2002 are output from the circuit characteristics although they are actually 0 A when the magnetic field applied to the magnetic element 50 is zero (in the case of zero magnetic field). Indicates the current value.

FIG. 3 is a diagram illustrating a configuration example of the magnetic element 50 which is a flux gate (FG) type magnetic element of the magnetic element 50 in the present embodiment.
The magnetic element 50 has three windings wound around the magnetic core 54. The first excitation coil 51 is composed of a first winding and the second winding is composed of a second winding. It consists of two excitation coils 52 and a detection coil 53 composed of a third system winding.
As can be seen from FIG. 3, the winding directions of the first excitation coil 51 and the second excitation coil 52 with respect to the magnetic core 54 are opposite. That is, the first excitation coil 51 is wound clockwise around the magnetic core 54, for example. On the other hand, the second excitation coil 52 differs from the first excitation coil 51 in the winding direction of the winding, and is wound counterclockwise around the magnetic core 54.

  The first excitation signal DR1 flowing through the first excitation coil 51 and the second excitation signal DR2 flowing through the second excitation coil 52 are opposite in the direction of current flow, and the winding direction of the winding of the first excitation coil 51 The winding direction of the winding of the second excitation coil 52 is opposite. For this reason, the direction of the magnetic field generated with respect to the longitudinal direction of the magnetic core 54 is the same. That is, the first excitation signal DR1 is a drive current that flows through the first excitation coil 51. The second excitation signal DR2 is a current that is 180 degrees out of phase with the first excitation signal DR1, and is a drive current that flows through the second excitation coil 52.

FIG. 4 is a diagram showing the temperature dependence of the offset in the zero magnetic field of each of the first excitation coil 51 and the second excitation coil 52. In FIG. 4, the horizontal axis indicates the temperature, and the vertical axis indicates the zero magnetic field output, that is, the magnitude of the offset. T0 is a reference temperature (for example, room temperature), and Vo indicates a voltage that is a zero magnetic field output at the reference temperature.
As shown in FIG. 4, since the differential amplifier 2001 has a positive temperature-dependent offset with respect to temperature, the offset (dashed line) increases as the temperature rises. Will increase. On the other hand, the differential amplifier 2002 has a temperature-dependent offset opposite to that of the differential amplifier 2001. Accordingly, since the differential amplifier 2002 has a negative temperature-dependent offset with respect to the temperature, the offset (broken line) decreases as the temperature increases, and the zero magnetic field output decreases.

The change ratio of the offset with respect to the temperature in the differential amplifier 2001 and the change ratio of the offset with respect to the temperature in the differential amplifier 2002 are designed and created so as to have the same absolute value.
Thereby, the offset value of the magnetic field generated in the magnetic core 54 is canceled by the change in the offset value due to the opposite polarities of the differential amplifier 2001 and the differential amplifier 2002 when the temperature changes. Therefore, the offset value of the zero magnetic field output can be a constant value that does not depend on the temperature change, and the temperature dependence of the output value of the detection coil 53 of the magnetic element 50 can be suppressed. This zero magnetic field output is a combination of offsets with the same ratio of rise and fall as described above, and becomes a constant value without depending on the temperature, so that it can be easily corrected when output.
Even when the winding direction of the exciting coil 51 and the exciting coil 52 shown in FIG. 3 is made the same without using the inverter 2003 shown in FIG. 2, it occurs in the longitudinal direction of the magnetic core 54 shown in FIG. The direction of the magnetic field is the same. Therefore, even when the polarities of the offset temperature characteristics of the differential amplifier 2002 and the differential amplifier 2003 of FIG. 2 are different and the absolute values are the same, the temperature dependence of the output value of the detection coil 53 of the magnetic element 50 is suppressed. Can do.

Further, in contrast to the process of supplying the excitation current to the excitation coil described with reference to FIG. 15, the magnetic element 50 shown in FIG. 3 has polarities for the first excitation coil 51 and the second excitation coil 52, respectively. The same magnetic field measurement process is performed except for the process of supplying different excitation currents.
In FIG. 15A, the first excitation signal DR1 (excitation current Id) is supplied to the first excitation coil 51 of the magnetic element 50, for example. In this case, in FIG. 15A, the vertical axis indicates the current value of the first excitation signal DR1, and the horizontal axis indicates time. Here, the waveform of the second excitation current DR2 whose phase is shifted by 180 degrees with respect to the first excitation current DR1 supplied to the first excitation coil 51 is omitted. That is, the second excitation current DR2 is supplied to the second excitation coil 52 with a phase shifted by 180 degrees from the first excitation current DR1.

As a result, the first excitation current DR1 and the second excitation current DR2 cancel each other offset due to the temperature dependence of the offsets of the polarities of the differential amplifier 2001 and the differential amplifier 2002 that are different from each other. As a result, the temperature dependence of the offset in the zero magnetic field at the magnetic flux density shown in FIG. 15B is eliminated, and the offset value can be controlled to a constant value regardless of the temperature.
Accordingly, since the temperature dependency of the offset is eliminated, the temperature dependency of the position of the pulse generated by the induced electromotive force in the detection coil of the magnetic element in FIG. 15C can be suppressed. That is, the temperature dependence of the output value of the magnetic element 50 can be suppressed. Further, the method for measuring the stationary magnetic field from pulses of different polarities (the first detection signal at time t1 and the second detection signal at time t2) in the description of FIG. 15 is the same as the description in the conventional example.

  Further, the magnetic field intensity generated by the excitation signal for the excitation coil depends on the current applied to the excitation signal adjustment unit 116. In the present embodiment, two of the first excitation coil 51 and the second excitation coil 52 are provided as excitation coils. For this reason, according to the present embodiment, the first excitation signal DR1 is applied to the first excitation coil 51 and the second excitation signal DR2 is applied to the second excitation coil 52, whereby the power supply voltage is reduced. The total sum of currents flowing through the first excitation coil 51 and the second excitation coil 52 can be increased without increasing it. Therefore, the pulse voltage generated by the induced electromotive force in the detection coil 53 can be increased according to the number of windings of the detection coil 53. By increasing the voltage value of the pulse generated by the induced electromotive force, it becomes possible to reduce the amplification factor when the voltage at both ends of the detection coil 53 is amplified, and noise caused by the amplifier characteristics of the detection signal amplification unit 111 It is possible to reduce the time variation of the output data signal.

Next, FIG. 5 is a flowchart for explaining an operation example of the magnetic element control processing of the magnetic element control apparatus 10 according to the present embodiment.
Step S1:
The detection signal amplification unit 111 amplifies the voltage across the detection coil 53 in the magnetic element 50 and outputs the amplified voltage to the detection signal comparison unit 112.

Step S2:
The detection signal comparison unit 112 compares the amplified voltage with a predetermined threshold, and uses a voltage that exceeds (or falls below) a predetermined threshold (a threshold for each of positive and negative voltages) as a detection signal.
That is, the detection signal comparison unit 112 detects the first detection signal and the second detection signal as detection signals. The detection signal comparison unit 112 outputs the first detection signal (corresponding to the pulse at time t1 in FIG. 15) and the second detection signal (corresponding to the pulse at time t2 in FIG. 15) (the intensity of the stationary magnetic field). , A pulse train having a duty ratio which is voltage information (hereinafter referred to as a pulse train) is generated based on time information corresponding to (Tm, T0, Tp, etc.).
Then, the detection signal comparison unit 112 outputs the generated pulse train to the time-output signal conversion unit 113 as voltage information (voltage information having information on the period in which the first detection signal and the second detection signal are output).

Step S3:
The time-output signal conversion unit 113 generates a DC voltage from the pulse train having the duty ratio supplied from the detection signal comparison unit 112 by using a PWM circuit or the like as a measurement voltage.
Then, the time-output signal conversion unit 113 outputs the generated measurement voltage to the data signal conversion unit 115.

Step S4:
When the measurement voltage is supplied from the time-output signal conversion unit 113, the data signal conversion unit 115 subtracts the offset voltage from the measurement voltage. This offset voltage is, for example, a steady offset value canceled by each of the differential amplifier 2001 and the differential amplifier 2002 in the present embodiment, and is measured experimentally in advance. Further, the data signal conversion unit 115 has a storage unit therein. In the storage unit inside the data signal conversion unit 115, a steady offset voltage obtained by experiment is written in advance.
Then, the data signal conversion unit 115 amplifies the measurement voltage corrected using the offset voltage with a preset amplification factor, and outputs the amplified signal to the data signal determination unit 104 as a data signal.

Step S5:
The data signal determination unit 104 determines whether the voltage value indicated by the data signal supplied from the data signal conversion unit 115 is included in the data range defined by the two threshold voltages set in the internal determination circuit. Judgment is made. At this time, if the voltage value indicated by the data signal is included in the data range, the data signal determination unit 104 advances the process to step S6. On the other hand, if the voltage value indicated by the data signal is not included in the data range, the data signal determination unit 104 advances the process to step S7. This data range shows a range in which the correspondence between the magnetic field strength and the voltage described later is linear.

Step S6:
Next, the data signal determination unit 104 outputs the data signal supplied from the data signal conversion unit 115 to an external magnetic field detection device.
This magnetic field detection device converts the voltage of the data signal into a digital value by A / D conversion, and is supplied from the magnetic element control device 10 from the magnetic field strength table stored in the internal storage unit by the converted digital value. The magnetic field intensity corresponding to the voltage value indicated by the data signal is read and displayed on its own display unit. Although the output data signal of the data signal determination unit 104 is an analog value, the output data signal can be digitized by A / D conversion in the magnetic element control device 10.

Step S7:
Next, the data signal determination unit 104 discards the data signal supplied from the data signal conversion unit 115 and outputs an error signal to an external magnetic field detection device.
As described above, when an error signal is supplied from the magnetic element control device 10, this magnetic field detection device sends a notification indicating that the applied stationary magnetic field cannot be measured to its display unit. indicate.

<Second Embodiment>
Hereinafter, a second embodiment of the present invention will be described with reference to the drawings. In the present embodiment, magnetic balance type magnetic detection processing is performed using an FG type magnetic element. FIG. 6 is a diagram for explaining a configuration of a magnetic detection device including the magnetic element control device 20 and the magnetic element 50 according to the second embodiment of the present invention. The magnetic element control device 20 includes a magnetic element control unit 21, a clock signal generation unit 102, a clock signal adjustment unit 103, and a data signal determination unit 104. The same code | symbol is attached | subjected to the structure similar to 1st Embodiment.

  The magnetic element control apparatus 20 according to the present embodiment uses a time-resolved magnetic field intensity to the strength of a stationary magnetic field applied to a fluxgate magnetic element 50 including a first excitation coil 51, a second excitation coil 52, and a detection coil 53. Detect by equilibrium type. When the magnetic element control device 20 detects the stationary magnetic field, the first excitation signal DR1 (first alternating signal) and the second excitation signal applied to each of the first excitation coil 51 and the second excitation coil 52. Each of DR2 (second alternating signal) is controlled. Since this embodiment performs magnetic balance control, the details will be described later, but unlike the first embodiment, the first excitation signal DR1 and the second excitation signal DR2 include feedback signals for magnetic balance. Superimposed.

  The magnetic element control unit 21 includes a detection signal amplification unit 211, a detection signal comparison unit 212, a time-output signal conversion unit 213, a feedback signal adjustment unit 214, a data signal conversion unit 215, an excitation signal adjustment unit 216, and an excitation signal generation unit 217. It has. Here, each of the detection signal amplification unit 211, the detection signal comparison unit 212, the time-output signal conversion unit 213, the data signal conversion unit 215, the excitation signal adjustment unit 216, and the excitation signal generation unit 217 is illustrated in FIG. Corresponds to the detection signal amplification unit 111, the detection signal comparison unit 112, the time-output signal conversion unit 113, the data signal conversion unit 115, the excitation signal adjustment unit 116, and the excitation signal generation unit 117. Hereinafter, operations different from those in FIG. 1 will be described.

In the magnetic element control unit 211, the excitation signal generation unit 217 generates an alternating signal, for example, a triangular wave signal as an alternating voltage signal that alternates with 0 V as a reference potential, based on the clock signal supplied from the clock signal adjustment unit 103. .
The excitation signal adjustment unit 216 amplifies the triangular wave signal generated by the excitation signal generation unit 217 at a predetermined amplification factor, generates a triangular wave current signal, and applies it to the excitation coil 52.
In addition, the excitation signal adjustment unit 216 applies a triangular wave current signal applied to each of the first excitation coil 51 and the second excitation coil 52, that is, a first excitation signal DR1 and a second excitation signal DR2 to be described later. Thus, the current components of the feedback current If and the period current -If are added.

  Next, FIG. 7 is a graph showing the operation principle of the fluxgate type magnetic element. FIG. 7A is a graph showing the change over time of the triangular wave voltage signal supplied to the exciting coil 52, with the vertical axis showing current and the horizontal axis showing time. In FIG. 7A, a triangular wave current signal (first excitation signal DR1) supplied to the first excitation coil 51 is a positive / negative alternating signal with a reference current (0A) as a boundary. In FIG. 7A, the current (reference current) on the vertical axis that intersects the horizontal axis is expressed as 0 A (zero ampere) (in the voltage notation, it is the standard reference voltage Vref). Although not shown in FIG. 7A, the triangular wave current signal (first excitation signal DR2) supplied to the second excitation coil 52 is the same as that of the first embodiment. Is 180 degrees out of phase with the triangular wave current signal supplied to. In FIG. 7B, the direction of current flow of the first excitation signal DR1 flowing through the first excitation coil 51 and the second excitation signal DR2 flowing through the first excitation coil 52 in FIG. The detection signal (the first detection signal at time t1 and the second detection signal at time t2) generated in the detection coil 51 by the induced electromotive force when the polarity of the excitation current changes thereby) It is a graph which shows the time change of. In FIG. 7B, the vertical axis represents voltage and the horizontal axis represents time.

Here, FIG. 7A shows a reference potential (reference potential) of the first excitation signal DR1 which is a triangular wave current signal applied to the first excitation coil 51 when the stationary magnetic field (Hex) is applied to the magnetic element 50. It shows that the current 0A) deviates from the reference current 0A (zero ampere) by the DC voltage that generates the applied stationary magnetic field. Although not shown, the reference potential (reference current 0A) of the second excitation signal DR2, which is a triangular wave current signal applied to the second excitation coil 52, is applied as in the case of the first excitation signal DR1. The reference voltage is deviated from 0 A (zero ampere) by the DC voltage that generates the magnetic field.
Further, the first detection signal (time t1) and the second detection signal (time t2) are generated in correspondence with the deviation of the first excitation signal DR1 and the second excitation signal DR2 due to the stationary magnetic field (Hex) in the reference current 0A. Indicates a time lag.

  Here, as can be seen from FIG. 7B, the time width Tw between the time t1 of the first detection signal and the time t2 of the second detection signal, and the time T / 2 that is ½ of the period T of the triangular wave, If the difference Td is 0, no stationary magnetic field (Hex) is applied to the magnetic element 50, and if the difference Td is positive, a negative stationary magnetic field (Hex <0) is applied. If it is negative, a positive stationary magnetic field (Hex> 0) is applied.

Returning to FIG. 6, the detection signal amplification unit 211 amplifies the voltage across the detection coil 53 of the magnetic element 50 with a preset amplification factor.
The detection signal comparison unit 212 compares the voltage value of the amplified detection signal supplied from the detection signal amplification unit 211 with a predetermined threshold voltage value, and compares the first detection signal and the second detection signal (FIG. 7). (B) is detected.
Here, as shown in FIG. 7B, the first detection signal is a negative pulse, and the polarity of the current of the first excitation signal DR1 applied to the first excitation coil 51 is positive to negative. The second excitation signal DR2 applied to the second excitation coil 52 is generated by induced electromotive force in a current region where the polarity of the current of the second excitation signal DR2 changes from negative to positive. On the other hand, the second detection signal is a positive pulse, and the polarity of the current of the first excitation signal DR1 applied to the first excitation coil 51 is negative to positive, and is applied to the second excitation coil 52. Generated by the induced electromotive force in a current region where the polarity of the current of the second excitation signal DR2 changes from positive to negative.
The detection signal comparison unit 212 obtains a difference between a time width (described later) between time t1 and time t2 of detection signals having different polarities and T / 2, and outputs this difference to the time-output signal conversion unit 213. To do.

  The time-output signal conversion unit 213 outputs voltage information as voltage information based on the output period of the first detection signal and the second detection signal (interval between time t1 and time t2 in FIG. 7B, that is, time width). A pulse having a duty ratio is generated, and this pulse is output as voltage information to the feedback signal adjustment unit 214. That is, the time-output signal conversion unit 213 obtains a duty ratio indicating the voltage value of the feedback signal from the time width as voltage information, and adjusts the rectangular wave corresponding to the duty ratio indicating the voltage value of the feedback signal as the feedback signal. Output to the unit 214.

The feedback signal adjusting unit 214 generates a DC voltage corresponding to the duty ratio by a PWM (Pulse Width Modulation) circuit or the like when the information is indicated by a rectangular wave signal. The feedback signal adjustment unit 214 converts the PWM signal into a DC signal using an integrator or the like, and outputs the DC signal to the excitation signal adjustment unit 216 as a feedback signal.
Further, the feedback signal adjustment unit 214 supplies voltage information indicating the voltage value of the DC voltage to the data signal conversion unit 215.

The data signal conversion unit 215 amplifies the voltage information supplied from the feedback signal adjustment unit 214 with a preset amplification degree and outputs the amplified voltage information to the data signal determination unit 104.
The amplification degree in the data signal conversion unit 215 is set to a value that outputs only the voltage value range of the feedback signal in a linearly measurable range in advance as a data signal. In other words, this amplification degree is a voltage obtained by amplifying only the range in which the magnetic field that cancels the stationary magnetic field and the feedback signal of the voltage value that generates this magnetic field maintain linearity, and the voltage outside the range is saturated to a constant voltage. It is what. In other words, the data signal conversion unit 215 sets in advance the voltage value of the feedback signal that is outside the voltage range of the feedback signal in which the voltage value converted into the feedback signal and the magnetic field intensity generated by this voltage value have linearity are saturated. The feedback signal is amplified by the amplification factor and output.

The data signal determination unit 104 determines whether or not the voltage value of the data signal supplied from the data signal conversion unit 215 is included in a preset data range (output data designation range). In the data signal determination unit 104, the data range is previously written and stored in an internal storage unit. This data range determines whether or not the voltage value indicated by the data signal amplified and output by the data signal conversion unit 215 is included in a region where the magnetic field and the voltage value indicating the magnetic field are in a linear relationship. It is a range of voltage values.
Here, when the voltage value of the data signal is not included in the data range, the data signal determination unit 104 outputs a data signal (error signal) indicating an error to the external magnetic field strength detection device. In addition, when the voltage value of the data signal is included in the data range, the data signal determination unit 104 outputs a data signal indicating the voltage value to the external magnetic field strength detection device.

In the processing in the feedback signal adjustment unit 214, for example, when the time width from the first detection signal to the second detection signal is longer than the time width from the second detection signal to the first detection signal, the stationary magnetic field is Must be negative. Therefore, the feedback signal adjustment unit 214 generates a DC voltage feedback signal that generates a positive magnetic field that cancels the stationary magnetic field.
On the other hand, when the time width from the second detection signal to the first detection signal is longer than the time width from the first detection signal to the second detection signal, the stationary magnetic field is positive. A DC voltage feedback signal that generates a negative magnetic field that cancels the stationary magnetic field is generated.

That is, when a pulse train that is voltage information is supplied, the feedback signal adjustment unit 214 generates a feedback signal having a current value corresponding to the duty ratio of this pulse, and the generated feedback signal is sent to the excitation signal adjustment unit 216. Output.
Here, the feedback signal adjustment unit 214 is provided with, for example, a voltage-current conversion circuit configured using an operational amplifier. In this voltage-current converter circuit, an amplifier with an operational amplifier function is used, and this amplifier functions so that the potential difference between the positive input and the negative input is maintained at zero. Therefore, the current signal from the amplifier output to the positive input is an external magnetic field. And is proportional.

  The excitation signal adjustment unit 216 superimposes the first feedback signal (If) supplied from the feedback signal adjustment unit 214 on the first excitation signal DR1 applied to the first excitation coil 51. Further, the excitation signal adjustment unit 216 superimposes a second feedback signal having a polarity opposite to that of the first feedback signal on the second excitation signal DR <b> 2 applied to the second excitation coil 52. Thereby, in the first exciting coil 51 and the second exciting coil 52, magnetic fields are generated by the first feedback signal and the second feedback signal, and the magnetic field generated in the magnetic core 54 in the magnetic element 50 is constant. To be adjusted. As a result, the time interval between the first detection signal and the second detection signal detected by the detection coil 53 can be kept constant (T / 2) without depending on the external stationary magnetic field.

  Next, FIG. 8 is a diagram illustrating a configuration example of the feedback signal adjustment unit 214, the excitation signal adjustment unit 216, and the excitation signal generation unit 217 in FIG. In FIG. 8, the excitation signal adjustment unit 216 includes a differential amplifier 2001 (first excitation signal generation unit), a differential amplifier 2002 (second excitation signal generation unit), an inverter 2003, and a resistor 2004. Here, the resistance value of the resistor 2004 is the resistance value R. The resistor 2004 is interposed between the output terminal of the excitation signal generator 217 and the (−) terminal (inverting input terminal) of the differential amplifier 2001 and the input terminal of the inverter 2003. The resistor 2004 converts the voltage Vex of the triangular wave excitation signal output from the excitation signal generation unit 217 into voltage and current, and supplies the voltage Vex to the (−) terminal of the operational amplifier 2001 as the drive current Iex.

Thereby, the differential amplifier 2001 supplies the drive current Iex to the first excitation coil 51.
In addition, the output terminal of the inverter 2003 is connected to the (−) terminal (inverting input terminal) of the operational amplifier 2002, the polarity of the current I is changed (the flow direction is reversed), and the (−) terminal of the operational amplifier 2002 is connected. Supply against. As a result, the differential amplifier 2002 supplies the second excitation coil 52 with a drive current having an absolute current value equal to that of the differential amplifier 2001 and having a different polarity.

The feedback signal adjustment unit 214 also provides a feedback signal adjustment unit 2141 that supplies a feedback current (If) to the differential amplifier 2001, and a feedback signal adjustment that supplies a feedback current (−If) to the differential amplifier 2002. Part 2142.
When a pulse train as voltage information is supplied, the feedback signal adjustment unit 2141 generates a first feedback signal (If) having a current value corresponding to the duty ratio of the pulse train, and this first feedback signal is used as the differential amplifier 2001. The (−) terminal is supplied. As a result, the first feedback signal is superimposed on the first excitation signal DR1 (Iex).

  In addition, when a pulse train as voltage information is supplied, the feedback signal adjustment unit 2142 generates a second feedback signal (−If) having a current value corresponding to the duty ratio of the pulse train, and the second feedback signal is differenced. This is supplied to the (−) terminal of the dynamic amplifier 2002. Thereby, the second feedback signal is superimposed on the second excitation signal DR2 (−Iex).

Next, FIG. 9 is a diagram illustrating another configuration example of the feedback signal adjustment unit 214, the excitation signal adjustment unit 216, and the excitation signal generation unit 217 in FIG. In FIG. 9, the excitation signal adjusting unit 216A includes a differential amplifier 2001 (first excitation signal generating unit), a differential amplifier 2002 (second excitation signal generating unit), an inverter 2003, and a resistor 2004. Here, the resistance value of the resistor 2004 is the resistance value R. The resistor 2004 is interposed between the output terminal of the excitation signal generator 217 and the (−) terminal (inverting input terminal) of the differential amplifier 2001 and the input terminal of the inverter 2003. The resistor 2004 converts the voltage Vex of the triangular wave excitation signal output from the excitation signal generation unit 217 into voltage and current, and supplies the converted voltage Vex to the (−) terminal of the operational amplifier 2001 as a drive current Iex.
The inverter 2003 has an output terminal connected to the (−) terminal (inverted input terminal) of the operational amplifier 2002, changes the polarity of the current I (with the direction of flow reversed), and is connected to the (−) terminal of the operational amplifier 2002. Supply. As a result, the differential amplifier 2002 supplies a drive current −Iex having a polarity different from that of the differential amplifier 2001 to the second excitation coil 52.

The feedback signal adjustment unit 214 includes a feedback signal adjustment unit 2141A and a feedback signal adjustment unit 2142A.
When a pulse train as voltage information is supplied, the feedback signal adjustment unit 2141A generates a first feedback signal (-If) having a current value corresponding to the duty ratio of the pulse train, and the first feedback signal is differential amplifier. This is supplied to the (+) terminal of 2001. As a result, the first feedback signal is superimposed on the first excitation signal DR1 (Iex).
Further, when a pulse train that is voltage information is supplied, the feedback signal adjusting unit 2142A generates a second feedback signal (If) having a current value corresponding to the duty ratio of the pulse train, and the second feedback signal is differentially generated. Supply to the (+) terminal of the amplifier 2002. Thereby, the second feedback signal is superimposed on the second excitation signal DR2 (−Iex).

Although the generation of the first feedback signal and the second feedback signal described above is based on analog processing, a configuration in which generation is performed by digital processing shown below may be used.
The detection signal comparison unit 212 measures the time width from the first detection signal to the second detection signal, and the time width Tw (Tp, Tm, etc.) and a time half of the period T of the triangular wave, that is, T / 2. The difference Td (= Tw− (T / 2)) is obtained and output to the feedback signal converter 1014.
When the difference Td that is time information is supplied from the detection signal comparison unit 212, the time-output signal conversion unit 213 generates voltage information that generates the voltage of the feedback signal as the FB signal from the difference Td.
Here, in the time-output signal conversion unit 213, a time voltage information table indicating the correspondence between the difference Td and the voltage information of the digital value corresponding to the difference Td is written and stored in advance in the internal storage unit. .

  The time-output signal conversion unit 213 reads voltage information corresponding to the supplied difference Td from the time voltage information table stored in the internal storage unit, and outputs the voltage information to the feedback signal adjustment unit 214. . For example, the voltage information is digital value data indicating the voltage value of the feedback signal. Moreover, the polarity of the difference Td is attached to the voltage information, that is, the voltage information has a positive polarity when the difference Td is positive, and has a negative polarity when the difference Td is negative. Accordingly, when a stationary magnetic field Hex having a positive polarity is applied to the magnetic element 50, the excitation signal adjustment unit 216A is negative with respect to the current value of the first excitation signal DR1 generated from the triangular wave voltage signal. When the polarity feedback current If is superimposed as a feedback signal, while the negative polarity stationary magnetic field Hex is applied, the polarity is positive with respect to the current value I of the first excitation signal DR1 generated from the triangular wave voltage signal. Is fed back as a first feedback signal. In addition, the excitation signal adjustment unit 216A superimposes a feedback current (−If) having a polarity different from that of the first excitation signal DR1 on the second excitation signal DR2 as a second feedback signal.

The feedback signal adjustment unit 214 generates a feedback signal having a voltage value indicated by the voltage information based on the voltage information supplied from the time-output signal conversion unit 213, and outputs the feedback signal as an FB signal to the excitation signal adjustment unit 216A.
Here, since the voltage information is a digital value, the feedback signal adjustment unit 214 includes a D / A converter, for example, and inputs the supplied voltage information, which is a digital value, to the D / A converter. A voltage is obtained, converted into a direct current, and output to the excitation signal adjustment unit 216A as a first feedback signal and a second feedback signal.
As described above, the excitation signal adjustment unit 216A supplies the first excitation signal DR1 on which the first feedback signal supplied from the feedback signal adjustment unit 214 is superimposed to the first excitation coil 51, thereby providing the second feedback. The second excitation signal DR2 on which the signal is superimposed is applied to the second excitation coil 52 as a triangular wave current signal.

Further, when the first feedback signal and the second feedback signal are superimposed on the first excitation signal DR1 and the second excitation signal DR2, respectively, the first detection signal and the second detection signal detected by the detection signal comparison unit 212. Is in the vicinity of T / 2.
For this reason, when the first feedback signal and the second feedback signal are already superimposed on each of the first excitation signal DR1 and the second excitation signal DR2, the detection signal comparison unit 212 outputs time information T / 2 shows the current value of the difference between the feedback signal required to set 2 and the currently applied feedback signal. Therefore, when the first excitation signal DR1 and the second excitation signal DR2 are applied, the detection signal comparison unit 212 uses the difference Td as time information indicating the difference current value described above to the time-output signal conversion unit 213. Output.

Further, when the difference Td, which is time information indicating the difference current value, is supplied, the time-output signal conversion unit 213 generates voltage information for generating a current value corresponding to the difference Td as described above. Are read from the time voltage information table stored in the internal storage unit and output to the feedback signal adjustment unit 214.
Further, the feedback signal adjustment unit 214 has a storage unit therein, and voltage information is accumulated and stored in the storage unit, and is output to the excitation signal adjustment unit 216A using the accumulated voltage information. A current of feedback signals (first feedback signal and second feedback signal) is generated and output to the excitation signal adjustment unit 216A.
Here, the feedback signal adjustment unit 214 determines whether or not the voltage information corresponding to the difference Td is included in a preset voltage range.

When the voltage information is not included in the set voltage range, the feedback signal adjustment unit 214 does not change the magnetic field even when applied to cancel the stationary magnetic field applied to the magnetic element 50. That is, it is determined as a small voltage that does not affect cancellation.
In other words, the feedback signal adjustment unit 214 determines an error in control accuracy when changing the magnetic field intensity, and determines that the time width of the first detection signal and the second detection signal is approximately T / 2. At this time, the feedback signal adjustment unit 214 discards the voltage information within the error range without adding it to the time information until immediately before the internal storage unit.

The data signal conversion unit 215 amplifies the voltage information supplied from the feedback signal adjustment unit 214 with a preset amplification degree, and outputs the amplified voltage information to the outside.
The amplification degree in the data signal conversion unit 215 is set to a value that outputs only the voltage value range of the feedback signal in a linearly measurable range in advance as a data signal. In other words, this amplification degree is a voltage obtained by amplifying only the range in which the magnetic field that cancels the stationary magnetic field and the feedback signal of the voltage value that generates this magnetic field maintain linearity, and the voltage outside the range is saturated to a constant voltage. It is what. That is, the data signal conversion unit 215 sets a preset amplification factor at which the voltage value of the feedback signal saturates outside the voltage range of the feedback signal in which the voltage value of the feedback signal and the magnetic field strength generated by the voltage value have linearity. By amplifying the feedback signal,

  Therefore, this data signal indicates the magnetic field voltage for obtaining the strength of the magnetic field for canceling the stationary magnetic field, that is, the strength of the stationary magnetic field. An external magnetic field strength detecting device (not shown) converts the voltage value of the magnetic field voltage indicated by the data signal into the magnetic field strength, and outputs the converted magnetic field strength.

Here, in the magnetic field strength detection device, a magnetic field strength table indicating the correspondence between the voltage value of the magnetic field voltage and the strength of the magnetic field corresponding to the voltage value of the magnetic field voltage is written and stored in advance in the internal storage unit. ing.
The magnetic field strength detection device reads the magnetic field strength corresponding to the voltage value of the magnetic field voltage indicated by the data signal supplied from the magnetic element control device 20 from the magnetic field strength table, and sets it as a numerical value of the strength of the stationary magnetic field (Hex) , Display on the display unit provided in itself. In the present invention, a magnetic detection device is constituted by the magnetic element control device 100 and the magnetic field intensity detection device (not shown) described above.

  Next, the operation of the magnetic element control apparatus 20 in the present embodiment will be described with reference to FIGS. FIG. 10 is a flowchart illustrating an operation example of the magnetic element control device 20 according to the second embodiment. In the second embodiment, a case where a feedback signal is generated by digital processing will be described. The configuration for generating the feedback signal by analog processing can be similarly performed by the operation of the flowchart of FIG.

Step S11:
The detection signal amplification unit 211 amplifies the voltage across the detection coil 53 and outputs the amplified voltage to the detection signal comparison unit 212.
Then, the detection signal comparison unit 212 subtracts the reference time width T / 2 from the time width Tw between the time t1 when the first detection signal is detected and the time t2 when the second detection signal is detected, The subtraction result difference Td is output to the time-output signal conversion unit 213 as time information. When this time information is converted into a digital value, it is desirable to use TDC (Time to Digital Converter) or the like.

Step S12:
Next, the time-output signal conversion unit 213 reads voltage information indicating the voltage value of the feedback signal corresponding to the difference Td, which is the supplied time information, from the time voltage information table stored in the storage unit. This time voltage information table is a table in which time information is associated with voltage information corresponding to the time information (that is, information indicating a voltage value corresponding to the magnetic field intensity for setting the difference Td to 0).
Then, the time-output signal conversion unit 213 outputs the read voltage information to the feedback signal adjustment unit 214.

Step S13:
Next, the feedback signal adjustment unit 214 stores feedback signals (first feedback signal and second feedback signal) that are stored in the internal storage unit and superimposed on the current first excitation signal DR1 and second excitation signal DR2. ) Is read immediately before.
Then, the feedback signal adjustment unit 214 adds the voltage information supplied from the detection signal to the voltage information read from the storage unit.
The feedback signal adjustment unit 214 generates a feedback signal having a current value corresponding to the voltage value indicated by the voltage information based on the voltage information of the addition result, and outputs the feedback signal to the excitation signal adjustment unit 216.
Further, the feedback signal adjustment unit 214 writes and stores the voltage information of the addition result as new immediately preceding voltage information in the internal storage unit, and stores this voltage information (digital value) to the data signal conversion unit 215. Output.

Step S14:
Next, the excitation signal adjustment unit 216 is supplied with the first feedback signal and the second feedback signal from the feedback signal adjustment unit 214.
Then, the excitation signal adjustment unit 216 superimposes the feedback signal supplied from the feedback signal adjustment unit 214 on the excitation signal generated from the triangular wave signal synchronized with the clock signal output from the clock signal adjustment unit 103. That is, the excitation signal adjustment unit 216 superimposes the first feedback signal on the first excitation signal DR1, and superimposes the second feedback signal on the second excitation signal DR2.
Then, the excitation signal adjustment unit 216 applies the first excitation signal DR1 to the first excitation coil 51, and applies the second excitation signal DR2 to the second excitation coil 52.

Step S15:
Next, the data signal conversion unit 215 performs offset adjustment of the voltage information supplied from the feedback signal adjustment unit 214 with a preset offset value and amplifies the voltage information with a preset amplification degree, and the amplification result is used as a data signal. The signal is output to the signal determination unit 104.

Step S16:
Next, the data signal determination unit 104 determines whether or not the voltage value indicated by the data signal is included in a preset data range.
At this time, if the voltage value indicated by the data signal is included in the data range, the data signal determination unit 104 proceeds with the process to step S17, while the voltage value indicated by the data signal is not included in the data range. Then, the process proceeds to step S18.

Step S17:
Next, since the data signal is included in the data range, the data signal determination unit 104 outputs the data signal as it is to a magnetic field strength detection device arranged outside.
Then, the external magnetic field strength detection device reads the magnetic field strength corresponding to the voltage value indicated by the supplied data signal from the magnetic field strength table stored in the internal storage unit, and reads the magnetic field strength read to its own display unit. indicate. Although the output data signal of the data signal determination unit 104 is an analog value, the output data signal can be digitized by A / D conversion in the magnetic element control device 10.

Step S18:
On the other hand, since the data signal is not included in the data range, the data signal determination unit 104 discards the data signal and outputs an error signal to the magnetic field strength detection device arranged outside.

At this time, for example, when an error signal is supplied, the magnetic field intensity detection device displays information for notifying the user that the measurement range is exceeded on its own display unit.
When the power is supplied, the magnetic element control device 20 performs the processing from step S11 to step S18 according to the flowchart shown in FIG.
Further, when the magnetic element control device 110 is powered on, the feedback signal adjustment unit 1013 resets the accumulated data of the voltage information in the internal storage unit, and writes 0 as an initial value.

  In the present embodiment, the first feedback signal and the second feedback signal, which are FB signals, are superimposed on the first excitation signal DR1 and the second excitation signal DR2, respectively, and the first excitation signal DR1 is superimposed on the first excitation coil 51. And the second excitation signal DR2 is applied to the second excitation coil 52. For this reason, according to the present embodiment, it is possible to simultaneously suppress both the temperature dependence of the magnetic sensitivity and the temperature dependence of the output value of the magnetic element. Further, since it can be used as the FB coil and the second excitation coil of the magnetic element provided with the FB coil used in the conventional magnetic balance type, there is no need to newly design the structure of the magnetic element. There is.

Here, in addition to reducing the size of the magnetic element, when the size of the magnetic element is equivalent to the magnetic balance type, the excitation efficiency is increased by using the FB coil region and increasing the number of excitation coils and detection coils. Thus, the measurement range of the stationary magnetic field can be further expanded, and the S / N (Signal / Noise) ratio of the detection signal in the detection coil can be improved.
In addition, according to the present embodiment, since the feedback signal is superimposed on the excitation signal together with the offset voltage, the offset voltage corresponding to the magnetic field intensity due to the surrounding environment is set in the offset voltage adjustment unit 1018, so that it is easy and accurate. It is possible to measure the magnetic field strength of the measurement object.

In addition, a period in which a measurement period having an arbitrary time width is generated in synchronization with the clock signal, the excitation signal is applied to the first excitation coil 51 and the second excitation coil 52, and the measurement process is performed, and the first excitation coil The periods in which the measurement is not performed by stopping the application of the excitation signal to 51 and the second excitation coil 52 are alternately provided, and the first excitation coil 51 and the second excitation coil 52 are intermittently operated. Here, as a matter of course, the first excitation coil 51 and the second excitation coil 52 need to cancel each other's temperature characteristics, and therefore need to be operated simply at the same timing.
Thereby, the heat generation of the magnetic element 50 itself is suppressed, and the magnetic field strength can be measured with higher accuracy by reducing the temperature change.

Further, by using this intermittent operation function to sequentially drive the excitation coils of a plurality of magnetic elements, it is possible to measure a steady magnetic field with a plurality of magnetic elements by one magnetic element control device.
For example, magnetic elements are provided so that the measurement axes of three magnetic elements, that is, the three axes of the x-axis, y-axis, and z-axis are orthogonal to each other, and the magnetic field strength and the direction of the magnetic field in a three-dimensional space are measured. It can be used to control the magnetic element on the other axis.

<Third Embodiment>
Hereinafter, a third embodiment of the present invention will be described with reference to the drawings. In the present embodiment, magnetic detection processing is performed by both a magnetic balance type and a magnetic proportional type using an FG type magnetic element. FIG. 11 is a diagram illustrating a configuration of a magnetic detection device including the magnetic element control device 30 and the magnetic element 50 according to the third embodiment of the present invention. The magnetic element control device 30 includes a magnetic element control unit 31, a clock signal generation unit 102, a clock signal adjustment unit 103, and a data signal determination unit 104. The same code | symbol is attached | subjected to the structure similar to 1st Embodiment or 2nd Embodiment.

The magnetic element control unit 31 includes a detection signal amplification unit 311, a detection signal comparison unit 312, a time-output signal conversion unit 313, a feedback signal adjustment unit 314, a data signal conversion unit 315, an excitation signal adjustment unit 316, An excitation signal generation unit 317, a first analog switch 321 and a second analog switch 322 are provided. Here, each of the detection signal amplification unit 311, the detection signal comparison unit 312, the time-output signal conversion unit 313, the feedback signal adjustment unit 314, the data signal conversion unit 315, the excitation signal adjustment unit 316, and the excitation signal generation unit 317 includes: The detection signal amplification unit 211, the detection signal comparison unit 212, the time-output signal conversion unit 213, the feedback signal adjustment unit 214, the data signal conversion unit 215, the excitation signal adjustment unit 216, and the excitation signal generation unit 217 in FIG. It has a function.
Hereinafter, differences from the respective configurations and operations of the magnetic element control device 20 of FIG. 6 will be described.

A different configuration from the third embodiment and the second embodiment is that it can cope with both magnetic balance type magnetic field measurement and magnetic proportional type magnetic field measurement.
That is, in the third embodiment, the user can arbitrarily select and switch the configuration of magnetic balance type magnetic field measurement in the second embodiment to the configuration of magnetic proportional type magnetic field measurement. Hereinafter, although the case where the process which produces | generates a feedback voltage is performed by a digital value is demonstrated, it is the same also when the production | generation of a feedback voltage is performed by an analog process.

In FIG. 11, each of the first analog switch 321 and the second analog switch 322 switches between a magnetic balance type configuration and a magnetic proportional type configuration.
That is, when the magnetic element control unit 31 detects that a changeover switch (not shown) of the magnetic element control device 30 is in a state indicating a control with a magnetic balance type configuration, the first analog switch 321 is turned on (ON). And the second analog switch 322 is turned off (OFF).
Thereby, the time-output conversion unit 313 outputs the difference Td indicating the time to the feedback signal adjustment unit 314, and the magnetic field measurement process similar to that of the second embodiment is performed.

On the other hand, when the magnetic element control unit 31 detects that a change-over switch (not shown) of the magnetic element control device 30 is in a state indicating control with a magnetic proportional configuration, the first analog switch 321 is turned off (OFF). And the second analog switch 322 is turned on (ON).
As a result, the time-output signal conversion unit 313 obtains voltage information corresponding to the time difference Td and then outputs the voltage information to the data signal conversion unit 315 without outputting the voltage information to the feedback signal adjustment unit 314. Will do.
When the changeover switch is in a state indicating control with a magnetic proportional type configuration, the time-output conversion unit 313 generates a voltage value indicating the magnetic field strength based on the difference Td supplied from the detection signal comparison unit 312. Output.

Here, in the time-output conversion unit 313, a magnetic proportional voltage table indicating the correspondence between the difference Td and the voltage value indicating the magnetic intensity corresponding to the difference Td is written and stored in advance in the internal storage unit. ing.
Then, the time-output conversion unit 313 reads the voltage value corresponding to the difference Td supplied from the detection signal comparison unit 312 from the magnetic proportional voltage table, and the amplification factor set corresponding to the case of the magnetic proportional equation Thus, the voltage value is amplified and output to the data signal determination unit 104. Similarly to the gain in the case of the magnetic proportional type, the gain in the case of the magnetic proportional type is also set to a value serving as a limiter for extracting only a region where the voltage value and the magnetic intensity are in a linear relationship.
Therefore, when the data signal conversion unit 315 has a magnetic balance type configuration, the data signal conversion unit 315 amplifies the voltage information supplied from the feedback signal adjustment unit 314 by an amplification factor set corresponding to the magnetic balance type case, and the data signal Is output to the data signal determination unit 104.
The data signal determination unit 104 also determines whether or not the magnetic proportional type is within a range in which a preset linear relationship is maintained, as in the case of the magnetic balance type.

  Next, the magnetic element control processing of the magnetic element control apparatus 130 in the third embodiment will be described with reference to FIGS. 11 and 12. FIG. 12 is a flowchart for explaining an operation example of a magnetic element control process (feedback voltage generation process using a digital value) performed by the magnetic element control apparatus 30 according to the third embodiment.

Step S21:
The detection signal amplification unit 311 amplifies the voltage across the detection coil 53 and outputs the amplified voltage to the detection signal comparison unit 1012.
The detection signal comparison unit 312 subtracts the reference time width T / 2 from the time width Tw between the time t1 when the first detection signal is detected and the time t2 when the second detection signal is detected, and the subtraction result Is output to the time-output signal converter 313 as measured time information.

Step S22:
The magnetic element control unit 31 sets the magnetic element control device 30 as a feedback control state (magnetic balance mode) indicating that the changeover switch uses the magnetic element control device 30 as a magnetic balance type configuration, or as a magnetic proportional type configuration. The state (magnetic proportional mode) indicating that the feedback control is not used is detected.
Here, when the changeover switch is in the magnetic balance mode, the magnetic element control unit 31 advances the process to step S23. On the other hand, when the changeover switch is in the magnetic proportional mode, the process advances to step S34.

Step S23:
Next, when the changeover switch is in the magnetic balance mode, the magnetic element control unit 31 sets the first analog switch 321 in the conductive state and the second analog switch 322 in the non-conductive state.
Accordingly, the time-output signal conversion unit 313 obtains a voltage value corresponding to the difference Td from the difference Td supplied from the detection signal comparison unit 312, and uses the obtained voltage value as voltage information to provide a feedback signal adjustment unit. Output to 314. The process for obtaining the voltage value from the difference Td is the same as in the second embodiment.

Step S24:
Next, the time-output signal conversion unit 313 obtains a voltage value corresponding to the difference Td from the difference Td supplied from the detection signal comparison unit 312, and uses the voltage value as voltage information to the feedback signal adjustment unit 314. Output.
When the voltage information is supplied, the feedback signal adjustment unit 314 adds the voltage value indicated by the voltage information to the voltage value of the feedback voltage immediately before written in its storage unit, and newly adds the addition result. The voltage value of the correct feedback voltage.

Step S25:
Next, the feedback signal adjustment unit 314 determines whether or not the current value of the new feedback current as the addition result is equal to or less than a preset maximum current (within a specified range). This maximum current is a first hot water threshold range (-) that defines a current value range of a feedback current (first feedback signal, second feedback signal) applied to the first exciting coil 51 or the second exciting coil 52. For example, when applied to the superimposed first excitation signal DR1 and second excitation signal DR3, the first excitation coil 51 and the second excitation coil 52 are damaged. The current value is set to about 90% of the current value of the absolute maximum rating.
At this time, if the feedback signal adjustment unit 314 is included in the first current threshold range, the process proceeds to step S26, and if not included in the first current threshold range, the process proceeds to step S28.
Further, when it is determined that the feedback current is included in the first current threshold range, the feedback signal adjustment unit 314 increments the count process of the counter provided therein, that is, the count value (the number of repetitions of the process) (count value). 1).

Step S26:
Next, the feedback signal adjustment unit 314 determines whether or not the count value of the counter provided therein is less than the count threshold value that is written and stored in advance in the internal storage unit (set in the internal storage unit). Make a decision.
At this time, if the count value of the counter is less than the count threshold value, the feedback signal adjustment unit 314 advances the process to step S27. If the count value is greater than or equal to the count threshold value, the feedback signal adjustment unit 314 advances the process to step S28.

  The count threshold value is set in consideration of a case where convergence does not occur when obtaining the feedback voltage. Therefore, the count threshold is a value of the feedback voltage for which a constant stationary magnetic field is applied to the magnetic element 50 and the magnetic field strength of the stationary magnetic field can be measured within an error range, that is, a feedback voltage for canceling the stationary magnetic field can be calculated. The number of calculation iterations is obtained. Then, based on the number of repetitions, for example, a numerical value obtained by multiplying the number of repetitions by an arbitrary multiple (an arbitrary numerical value such as 2) is used as a count threshold, and the feedback signal adjustment unit 314 writes and stores it in a storage unit included therein. deep.

Step S27:
Next, the feedback signal adjustment unit 314 sets the absolute value of the feedback signal (first feedback signal and second feedback signal) generated from the voltage value of the voltage information obtained from the difference Td to a preset second current threshold value. It is determined whether or not it is less than.
At this time, if the current value of the feedback signal generated from the voltage value of the voltage information obtained from the difference Td is greater than or equal to the second current threshold value, the feedback signal adjustment unit 314 proceeds to step S30, while the feedback signal If the current value is less than the second current threshold, the process proceeds to step S29.
Here, the second current threshold range determines whether or not the current value changes the magnetic field strength exceeding the measurement error even if it is added to the current value of the current feedback signal. Therefore, the feedback signal adjustment unit 314 determines that the current value included in the second current threshold range is a current value that only gives a change in magnetic field strength within an error in measurement, and voltage information that generates the current value of this feedback signal Is not added to the feedback voltage accumulated in the internal storage unit. In addition, the second current threshold range is obtained by experiments or the like, and is written and stored in advance in a storage unit inside the feedback signal adjustment unit 314.

Step S28:
The feedback signal adjustment unit 314 determines that the stationary magnetic field currently applied to the magnetic element 50 cannot be measured, and outputs an error signal to the external magnetic field strength detection device via the data signal determination unit 104.
When the error signal is supplied, the magnetic field strength detection device displays a notification indicating that the stationary magnetic field currently applied to the magnetic element 50 cannot be measured on its display unit.

Step S29:
Next, the feedback signal adjustment unit 314 writes and stores the newly obtained feedback voltage as an immediately preceding feedback voltage in the internal storage unit.
Further, the feedback signal adjustment unit 314 generates a first feedback signal (If) and a second feedback signal (−If) corresponding to the voltage value of the newly obtained feedback voltage, and the excitation signal adjustment unit 316 Output.
Then, the excitation signal adjustment unit 316 generates a triangular wave current signal from the triangular wave supplied from the excitation signal generation unit 317.
The excitation signal adjustment unit 1016 superimposes the first feedback signal supplied from the feedback signal adjustment unit 314 on the first excitation signal DR1 and the second feedback signal on the second excitation signal DR2 with respect to the generated triangular wave current signal. They are superimposed and applied to the first excitation coil 51 and the second excitation coil 52, respectively. Thereafter, the excitation signal adjustment unit 316 returns the process to step S21.

Step S30:
Next, the feedback signal adjustment unit 316 reads the voltage value of the feedback voltage stored in the internal storage unit and outputs it to the data signal conversion unit 315.
Then, the data signal conversion unit 1015 amplifies the voltage value of the feedback voltage supplied from the feedback signal adjustment unit 1013 with a preset amplification factor, and outputs it as a data signal to the data signal determination unit 104.

Step S31:
Next, the data signal determination unit 104 determines whether or not the voltage value indicated by the data signal supplied from the data signal conversion unit 315 is included in the data range stored in the internal storage unit. At this time, if the voltage value indicated by the data signal is included in the data range, the data signal determination unit 104 advances the process to step S32. On the other hand, if the voltage value indicated by the data signal is not included in the data range, the data signal determination unit 104 advances the process to step S33.

Step S32:
Next, the data signal determination unit 104 outputs the data signal supplied from the data signal conversion unit 315 to an external magnetic field detection device.
As described above, the magnetic field detection device reads the magnetic field strength corresponding to the voltage value indicated by the data signal supplied from the magnetic element control device 30 from the magnetic field strength table stored in the internal storage unit, Is displayed on the display section.

Step S33:
Next, the data signal determination unit 104 discards the data signal supplied from the data signal conversion unit 315 and outputs an error signal to the external magnetic field detection device.
As described above, when an error signal is supplied from the magnetic element control device 30, the magnetic field detection device sends a notification indicating that the applied stationary magnetic field cannot be measured to its display unit. indicate.

Step S34:
Next, when the changeover switch is in the magnetic proportional mode, the magnetic element control unit 31 sets the first analog switch 321 in a non-conductive state and the second analog switch 322 in a conductive state.
Accordingly, the time-output signal conversion unit 313 has a configuration indicating the control in which the change-over switch has a magnetic proportional configuration, and thus the voltage indicating the magnetic field strength based on the difference Td supplied from the detection signal comparison unit 312. The value is output to the data signal conversion unit 315.

Step S35:
Next, the time-output signal conversion unit 313 obtains a voltage value indicating the magnetic field intensity based on the difference Td supplied from the detection signal comparison unit 312, and outputs the obtained voltage value to the data signal conversion unit 315. .
The detection of the magnetic field intensity by this magnetic field proportional expression is the same as in the case of the conventional example already described.

  Next, another magnetic element control process of the magnetic element control device 30 according to the third embodiment will be described with reference to FIGS. 11 and 13. FIG. 13 is a flowchart illustrating an operation example of a magnetic element control process (a process for generating a feedback voltage based on an analog value) performed by the magnetic element control apparatus 130 according to the third embodiment.

Step S41:
The magnetic element control unit 31 uses the magnetic element control device 30 as a state in which the change-over switch indicates that the magnetic element control device 30 is used as a magnetic balance configuration (magnetic balance mode) or as a magnetic proportional configuration. Is detected (magnetic proportional mode).
Here, when the changeover switch is in the magnetic balance mode, the magnetic element control unit 31 advances the process to step S42. On the other hand, when the changeover switch is in the magnetic proportional mode, the process advances to step S51.

Step S42:
Next, when the changeover switch is in the magnetic balance mode, the magnetic element control unit 31 sets the first analog switch 321 in the conductive state and the second analog switch 322 in the non-conductive state.
Thereby, the magnetic element control apparatus 30 becomes a structure which performs the detection of the magnetic field intensity by a magnetic balance type.

Step S43:
Next, the detection signal amplification unit 311 amplifies the voltage across the detection coil 53 with a predetermined amplification factor set in advance, and outputs the amplified voltage to the detection signal comparison unit 312.
Then, the detection signal comparison unit 312 outputs the detected first detection signal and second detection signal to the time-output signal conversion unit 313 as time information.

Step S44:
When the detection signal is supplied, the time-output signal conversion unit 313, based on the output period (time information) of the first detection signal and the second detection signal, a train of pulses having a duty ratio as voltage information ( A pulse train having the duty ratio is output to the feedback signal adjustment unit 314 as voltage information.

Step S45:
The feedback signal adjustment unit 314 generates a DC voltage from a pulse train having a supplied duty ratio by a PWM circuit or the like, and a feedback signal having a current value corresponding to the DC voltage (first feedback signal and second feedback signal). ) And output to the excitation signal adjustment unit 316.
Here, the feedback signal adjustment unit 314 is provided with, for example, a voltage-current conversion circuit configured using an operational amplifier. In this voltage-current converter circuit, an amplifier with an operational amplifier function is used, and this amplifier functions so that the potential difference between the positive input and the negative input is maintained at zero. Therefore, the current signal from the amplifier output to the positive input is an external magnetic field. And is proportional.

  A signal proportional to the current signal is applied as a feedback signal (first feedback signal and second feedback signal) to the excitation coils (the first excitation coil 51 and the second excitation coil 52). The magnetic field is generated and adjusted so that the magnetic field applied to the magnetic core in the magnetic element 50 is constant. As a result, the time interval between the first detection signal and the second detection signal can be kept constant (T / 2) without depending on the external stationary magnetic field. Here, the feedback signal adjustment unit 314 generates a first feedback signal from the DC voltage generated by the PWM circuit using a pulse train, and outputs a current having the same current value that is different in polarity from the current of the first feedback signal. Generated as a feedback signal.

Step S46:
Next, the excitation signal adjustment unit 316 includes a first excitation signal DR1 and a second excitation signal, which are triangular wave current signals generated from a triangular wave, for each of the first feedback signal and the second period signal supplied from the feedback signal adjustment unit 314. It is superimposed on each of the signals DR2.
Then, the excitation signal adjustment unit 316 applies the generated first excitation signal DR1 to the first excitation coil 51, and applies the second excitation current DR2 to the second excitation coil 52.

Step S47:
Next, the feedback signal adjustment unit 314 outputs, to the data signal conversion unit 315, a DC voltage generated by a pulse circuit having a duty ratio, which is generated by an integrator, using a PWM circuit or the like.
Then, the data signal conversion unit 315 offset adjusts the voltage value of the DC voltage supplied from the feedback signal adjustment unit 314 with a preset offset value, amplifies it with a preset amplification factor, and amplifies the result. The data signal is output to the data signal determination unit 104.

Step S48:
Next, in the data signal determination unit 104, the voltage value indicated by the data signal supplied from the data signal conversion unit 315 is included in the data range defined by the two threshold voltages set in the internal determination circuit. It is determined whether or not At this time, if the voltage value indicated by the data signal is included in the data range, the data signal determination unit 104 advances the process to step S49. On the other hand, if the voltage value indicated by the data signal is not included in the data range, the data signal determination unit 104 advances the process to step S50.

Step S49:
Next, the data signal determination unit 104 outputs the data signal supplied from the data signal conversion unit 315 to an external magnetic field detection device.
As described above, this magnetic field detection device converts the voltage of the data signal into a digital value by A / D conversion, and controls the magnetic element from the magnetic field strength table stored in the internal storage unit by the converted digital value. The magnetic field intensity corresponding to the voltage value indicated by the data signal supplied from the device 30 is read and displayed on its own display unit. As in the first embodiment, the output data signal of the data signal determination unit 104 is an analog value. However, the output data signal can be digitized by A / D conversion in the magnetic element control device 10. is there.

Step S50:
Next, the data signal determination unit 104 discards the data signal supplied from the data signal conversion unit 315 and outputs an error signal to the external magnetic field detection device.
As described above, when an error signal is supplied from the magnetic element control device 30, the magnetic field detection device sends a notification indicating that the applied stationary magnetic field cannot be measured to its display unit. indicate.

Step S51:
Next, when the changeover switch is in the magnetic proportional mode, the magnetic element control unit 31 sets the first analog switch 321 in a non-conductive state and the second analog switch 322 in a conductive state.
Accordingly, the time-output signal conversion unit 313 has a configuration indicating the control in which the change-over switch has a magnetic proportional configuration, and thus the voltage indicating the magnetic field strength based on the difference Td supplied from the detection signal comparison unit 312. The value is output to the data signal conversion unit 315.

Step S52:
Next, the detection signal amplification unit 311 amplifies the voltage across the detection coil 53 and outputs the amplified voltage to the detection signal comparison unit 312.
Then, the detection signal comparison unit 312 outputs the detected first detection signal and second detection signal to the time-output signal conversion unit 313 as time information.

Step S53:
When the detection signal is supplied, the time-output signal conversion unit 313, based on the output period (time information) of the first detection signal and the second detection signal, a train of pulses having a duty ratio as voltage information ( The pulse train) is generated, and the pulse train having this duty ratio is output to the data signal converter 315 as voltage information.
The data signal conversion unit 35 generates a DC voltage using a pulse train having a supplied duty ratio as a measurement voltage by a PWM circuit or the like. In the subsequent step S37, processing is performed using the measurement voltage as a feedback signal.

In the third embodiment described above, by controlling the conduction state of each of the first analog switch 321 and the second analog switch 322, the magnetic element control device 30 can be configured to measure the magnetic field by the magnetic balance type or the magnetic proportional type. It can be used by switching to any one of the magnetic field measurement configurations.
In the third embodiment, the first analog switch 321 is turned off and the second analog switch 322 is turned on, so that the feedback signal (first feedback signal, second feedback signal) is a triangular current signal. It is not superposed on the excitation signals (first excitation signal DR1, second excitation signal DR2). That is, the voltage for canceling the stationary magnetic field is directly converted into the magnetic field strength as the measurement voltage without superimposing the feedback signal for canceling the stationary magnetic field applied to the magnetic element 50 on the excitation signal. The configuration is realized by a simple circuit.

  In the present embodiment, the first feedback signal and the second feedback signal, which are FB signals, are superimposed on the first excitation signal DR1 and the second excitation signal DR2, respectively, and the first excitation signal DR1 is used as the first excitation signal. The second excitation signal DR2 is applied to the coil 51 and the second excitation signal DR2 is applied to the second excitation coil 52. For this reason, according to the present embodiment, both the temperature dependence of the magnetic sensitivity and the temperature dependence of the output value of the magnetic element can be simultaneously suppressed, as in the first embodiment. Since it can be used as the FB coil and the second excitation coil of the magnetic element provided with the FB coil used in the conventional magnetic balance type, there is an advantage that it is not necessary to newly design the structure of the magnetic element. .

Here, in addition to reducing the size of the magnetic element, when the size of the magnetic element is equivalent to the magnetic balance type, the excitation efficiency is increased by using the FB coil region and increasing the number of excitation coils and detection coils. Thus, the measurement range of the stationary magnetic field can be further expanded, and the S / N (Signal / Noise) ratio of the detection signal in the detection coil can be improved.
In addition, according to the present embodiment, since the feedback signal is superimposed on the excitation signal together with the offset voltage, the offset voltage corresponding to the magnetic field intensity due to the surrounding environment is set in the offset voltage adjustment unit 1018, so that it is easy and accurate. It is possible to measure the magnetic field strength of the measurement object.

Furthermore, according to the present embodiment, in the case of magnetic field measurement using a magnetic proportional formula (when the first analog switch 321 is in a non-conductive state and the second analog switch 322 is in a conductive state), the magnetic field measurement is limited to the excitation current and the excitation efficiency. Consider the measurement of the stationary magnetic field to be measured corresponding to the measurement magnetic field range. This provides good linearity between the magnetic field and the measured voltage measured. Furthermore, when measuring a stationary magnetic field within the measurement magnetic field range in this magnetic proportional expression, it is not necessary to generate an FB signal, so that current consumption can be suppressed.
On the other hand, when the measurement magnetic field range is wide, that is, when the magnetic field measurement is performed in a range in which the magnetic field intensity is larger than the measurement magnetic field range in the magnetic proportional type (when the first analog switch 321 is conductive and the second analog switch 322 is non-conductive). As in the first and second embodiments, it is necessary to perform magnetic field measurement by a magnetic balance type. With this magnetic balance type, linearity between the magnetic field and the feedback signal can be obtained in a wide range of magnetic field strength.

In addition, a period in which a measurement period having an arbitrary time width is generated in synchronization with the clock signal, the excitation signal is applied to the first excitation coil 51 and the second excitation coil 52, and the measurement process is performed, and the first excitation coil The periods in which the measurement is not performed by stopping the application of the excitation signal to 51 and the second excitation coil 52 are alternately provided, and the first excitation coil 51 and the second excitation coil 52 are intermittently operated. Here, as a matter of course, the first excitation coil 51 and the second excitation coil 52 need to cancel each other's temperature characteristics, and therefore need to be intermittently operated at the same timing.
Thereby, the heat generation of the magnetic element 50 itself is suppressed, and the magnetic field strength can be measured with higher accuracy by reducing the temperature change.

Further, similarly to the second embodiment, by using this intermittent operation function, the excitation coils of a plurality of magnetic elements are sequentially driven, so that a single magnetic element control device allows a plurality of magnetic elements to generate a steady magnetic field. Can be measured.
For example, magnetic elements are provided so that the measurement axes of three magnetic elements, that is, the three axes of the x-axis, y-axis, and z-axis are orthogonal to each other, and the magnetic field strength and the direction of the magnetic field in a three-dimensional space are measured. It can be used to control the magnetic element on the other axis.

  Further, a program for realizing the functions of each of the magnetic element control unit 11 of FIG. 1, the magnetic element control unit 21 of FIG. 6, and the magnetic control unit 31 of FIG. Magnetic element control processing may be performed by recording the program on a computer-readable recording medium, reading the program recorded on the recording medium into a computer system, and executing the program. Here, the “computer system” includes an OS and hardware such as peripheral devices.

Further, the “computer system” includes a homepage providing environment (or display environment) if a WWW system is used.
The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Furthermore, the “computer-readable recording medium” dynamically holds a program for a short time like a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line. In this case, a volatile memory in a computer system serving as a server or a client in that case, and a program that holds a program for a certain period of time are also included. The program may be a program for realizing a part of the functions described above, and may be a program capable of realizing the functions described above in combination with a program already recorded in a computer system.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes design and the like within a scope not departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 50 ... Magnetic element 51 ... 1st excitation coil 52 ... 2nd excitation coil 53 ... Detection coil 54 ... Magnetic body core 10, 20, 30 ... Magnetic element control apparatus 11, 21, 31 ... Magnetic element control part 102 ... Clock signal generation Unit 103 ... clock signal adjustment unit 104 ... data signal determination unit 111, 211, 311 ... detection signal amplification unit 112, 212, 312 ... detection signal comparison unit 113, 213, 313 ... time-output signal conversion unit 214, 314, 2141 , 2142, 2141A, 2142A ... feedback signal adjustment unit 115, 215, 315 ... data signal conversion unit 116, 216, 216A, 316 ... excitation signal adjustment unit 117, 217, 317 ... excitation signal generation unit 2001, 2002 ... differential amplifier 2003 ... Inverter 2004 ... Resistance

Claims (7)

Waveforms of pulse-like signals with different polarities detected by applying alternating signals to a plurality of exciting coils provided in the magnetic core and detecting from the detection coils provided in the magnetic core in accordance with the alternating signals Is a magnetic element control device that controls a magnetic element that detects a stationary magnetic field based on a detection interval of pulse signals having different polarities,
A first excitation signal generating unit that generates a first alternating signal in the alternating signal , which is an excitation signal subjected to current control applied to the first exciting coil among the exciting coils;
Synchronized with the first alternating signal in the alternating signal , which is an excitation signal with current control applied to a second exciting coil whose winding direction is opposite to that of the first exciting coil among the exciting coils. A second excitation signal generator for generating second alternating signals having different polarities;
A detection signal comparison unit that detects a detection signal of positive or negative voltage generated by an induced electromotive force when the current direction of the alternating signal is switched , and the first excitation signal generation unit and the second excitation signal generation unit the magnetic element control device the polarity of the change of the offset, characterized in reverse der Rukoto in positive and negative temperature characteristics in each. 2. The magnetic element control device according to claim 1, wherein the second excitation signal generation unit includes a circuit that reverses a polarity of a signal change with respect to a reference potential in the first excitation signal generation unit. An output signal generation unit that converts a time width between detection signals of positive voltage and negative voltage into voltage information;
The magnetic element control device according to claim 1, further comprising: a data signal conversion unit that outputs the voltage information as a data signal indicating a magnetic field strength. A feedback signal generation unit that converts a time width between detection signals of a positive voltage and a negative voltage into voltage information;
A feedback signal adjusting unit that generates a feedback signal to be applied to the feedback coil in order to cause the feedback coil to generate a magnetic field that cancels a stationary magnetic field applied to the magnetic element from the voltage information;
The magnetic element control device according to claim 1, further comprising: a data signal conversion unit that outputs the feedback signal as a data signal indicating a magnetic field strength. Each of the first excitation signal generator and the second excitation signal generator is
The magnetic element control device according to claim 4, further comprising an excitation signal generation circuit that superimposes the feedback signal on each of the first alternating signal and the second alternating signal. Waveforms of pulse-like signals with different polarities detected by applying alternating signals to a plurality of exciting coils provided in the magnetic core and detecting from the detection coils provided in the magnetic core in accordance with the alternating signals Is a magnetic element control method for controlling a magnetic element for detecting a stationary magnetic field according to a detection interval of pulse signals having different polarities,
A first excitation signal generating process for generating a first alternating signal in the alternating signal , which is an excitation signal subjected to current control , applied to the first exciting coil among the exciting coils;
Synchronized with the first alternating signal in the alternating signal , which is an excitation signal with current control applied to a second exciting coil whose winding direction is opposite to that of the first exciting coil among the exciting coils. A second excitation signal generation process for generating a second alternating signal having different polarities;
A detection signal comparison process for detecting a detection signal of a positive or negative voltage generated by an induced electromotive force when the current direction of the alternating signal is switched , the first excitation signal generation process and the second excitation signal generation process magnetic element control methods polarity of the offset changes in each are characterized inverse der Rukoto in positive and negative temperature characteristics. A magnetic detection device for detecting the strength of an applied stationary magnetic field;
A fluxgate type magnetic element comprising a first excitation coil, a second excitation coil and a detection coil;
An excitation signal generator for generating an alternating signal;
A first excitation signal generating unit that generates a first alternating signal in the alternating signal , which is an excitation signal that is applied to the first exciting coil and is current controlled ;
The second excitation coil is a current-controlled excitation signal applied to a second excitation coil having a winding direction opposite to that of the first excitation coil. A second excitation signal generator for generating an alternating signal of
A detection signal comparator for detecting a positive or negative voltage detection signal generated by an induced electromotive force when the current direction of the alternating signal is switched ;
A data signal conversion unit that outputs a data signal indicating a magnetic field intensity based on an interval of the detection signals of positive or negative voltage, and an offset of each of the first excitation signal generation unit and the second excitation signal generation unit. magnetic detection device, wherein the polarity of the change Ru reverse der in positive and negative temperature characteristics.

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