WO2014208105A1 - Magnetic sensor element with temperature correction, and magnetic sensor and power measuring device using same - Google Patents

Abstract

Magnetoresistance-type magnetic sensors have suffered from a problem in which an increase in the ambient temperature results in the degradation of the magnetic characteristics of the sensor magnetic film itself and thus results in the degradation of the sensor sensitivity. A magnetic sensor element with temperature correction according to the present invention is characterized by having a magnetic body exhibiting magnetoresistance, a pair of electrodes that oppose each other with the magnetic body therebetween and are for causing current to flow through the magnetic body, a vertical bias magnetic field addition means for generating a first bias magnetic field in the direction of the opposition of the electrodes, and a horizontal bias magnetic field addition means for generating a second bias magnetic field in the direction perpendicular to the vertical bias magnetic field addition means, and is characterized in that the temperature characteristic of the vertical bias magnetic field addition means is larger than the temperature characteristic of the horizontal bias magnetic field addition means.

Description

Temperature compensated magnetic sensor element and magnetic sensor and power measuring device using the same

The present invention relates to a magnetic sensor element provided with a temperature compensation function, and a magnetic sensor and a power measuring device using the magnetic sensor element.

The use of small magnetic sensors is expected to expand further. In particular, the power meter is considered an indispensable device when aiming to use electric energy from petrochemical fuel. In Patent Document 1, a magnetic sensor and a sensor resistor are connected in series, and the power consumption in the load can be measured by installing the sensor in parallel with the load in the electric circuit and adjacent to the wiring of the electric circuit. A power measurement device is disclosed.

Since such a power measuring device can be formed almost in the size of a magnetic thin film, the entire device can be manufactured in a size of about several mm square. Therefore, it is possible to monitor the power consumption in detail by installing it at various locations in a large-scale system.

On the other hand, if the application spreads, the environment where the use is planned is assumed to be a severe environment. In particular, temperature is known to change magnetic characteristics, and temperature compensation is an indispensable technique for magnetic sensors in order to improve the accuracy of sensor sensitivity.

In view of this problem, Patent Document 2 discloses a temperature-compensated magnetoresistive element circuit in which a bridge circuit is configured by magnetoresistive effect elements and no zero point drift occurs even when the temperature rises.

WO2012 / 105459 Japanese Patent Laid-Open No. 8-242427

When there is a zero point drift, a technique for performing temperature compensation using a bridge circuit or differential amplification is well known. The above Patent Document 2 also attempts to cancel the temperature characteristic of the magnetoresistive element by using a bridge circuit and prevent zero point drift.

However, such a circuit configuration is effective when the linearity of the element is high, but cannot be effective when the linearity of the output characteristic of the element is not high like a magnetoresistive element. Here, “high linearity” means that a region where the output can be regarded as linearly proportional to the input is wide.

The magnetoresistive element has a slight change in resistance value with respect to a magnetic field applied from the outside, and the magnetoresistive effect itself is a narrow characteristic in a linear region. Therefore, when the magnetoresistive effect is changed by increasing the temperature of the element, the dynamic range of the output with respect to the input is changed.

Therefore, when performing the so-called ON / OFF detection that detects the presence or absence of a magnetic substance with a magnetoresistive element, even if temperature compensation by a bridge circuit or the like is sufficient, quantitative characteristics such as current detection or power detection can be achieved. The temperature compensation in the problem was not enough.

The present invention has been conceived in view of the above problems, and provides a temperature-compensated magnetic sensor element in which the dynamic range does not change greatly even when the temperature rises or falls. It is another object of the present invention to provide a temperature-compensated magnetic sensor element with little output temperature dependency with respect to a predetermined input magnetic field.

More specifically, the magnetic sensor element with temperature compensation according to the present invention is:
A magnetic body having a magnetoresistive effect, and a pair of electrodes facing each other through the magnetic body in order to pass a current through the magnetic body,
Lateral bias magnetic field applying means for generating a bias magnetic field in a direction perpendicular to the opposing direction of the electrodes;
Having electrodes at both ends, one end electrode having a temperature compensating metal connected in series to the other end of the pair of electrodes,
When the resistance value at the reference temperature between the pair of electrodes is R _B0 and the resistance value at the reference temperature between the electrodes of the temperature compensating metal is R _A0 , within 10% of the relationship of the equation (9) It satisfies that it is included in the range.

Here, α _A is a temperature coefficient related to the electric resistance of the temperature compensating metal, α _B is a temperature coefficient related to the electric resistance of the magnetic material, β ₀ is a value of the magnetoresistance effect at the reference temperature, and β _B is a magnetic resistance. The temperature coefficient related to the effect, t is the temperature change from the reference temperature, ΔVMR is the output voltage obtained from both ends of the magnetic material by the magnetoresistive effect, H ₀ is the externally applied magnetic field, and V ₀ is the voltage applied to the magnetic material It is.

The magnetic sensor element with temperature compensation according to the present invention has a certain relationship between the resistance ratio of the magnetoresistive element and the temperature compensating metal, so that the dynamic range of the output voltage can be maintained even if the temperature changes within a predetermined range. It has the effect of hardly changing.

Also, a magnetic sensor and a power measuring device using this temperature-compensated magnetic sensor element can maintain sensitivity accuracy even under severe temperature changes, and contribute to the construction of a highly reliable system.

It is a figure explaining the principle of the temperature compensation which concerns on this invention. It is a figure which shows the structure of the magnetic sensor element with a temperature compensation which concerns on this invention. It is a figure which shows the structure of the electric power measuring apparatus using the magnetic sensor element with a temperature compensation which concerns on this invention. It is a figure which shows the relationship between resistance of NTC thermistor, and temperature. It is a figure which shows the structure of the magnetic sensor element which has the autonomous temperature compensation function using NTC thermistor. It is a figure which shows the structure of the magnetic sensor element which concerns on Embodiment 4. FIG. It is a figure which shows the structure of the sensor part which has an arrow feather pattern. It is a graph showing the change of a bridge gain. It is a graph which shows the result of having measured the temperature characteristic of the resistance value and resistance value sensitivity of the sensor part which was actually produced. It is a graph which shows the characteristic for compensation calculated | required by substituting the measured value of the sensor part actually produced for (43) Formula. It is a graph which shows a temperature characteristic when NTC thermistor is made constant and the resistance connected in parallel is changed. It is a graph which shows the temperature characteristic when resistance connected in parallel is made into a fixed value and the resistance value of NTC thermistor was changed. It is the graph which compared the combined resistance value and theoretical value of the bridge resistance which gave the temperature characteristic for compensation, and the compensation resistance. It is a graph which shows the result of having simulated the effect of the temperature compensation function. It is a figure which shows the structure of the magnetic sensor element which concerns on Embodiment 5. FIG. It is a graph which shows the result of having actually measured the magnetoresistive effect in case a longitudinal bias magnetic field differs. It is the graph which measured the relationship between the intensity | strength of a longitudinal bias magnetic field, and differential resistance value sensitivity. It is the graph which measured the differential resistance value sensitivity when changing a longitudinal bias magnetic field. It is the graph which calculated | required the magnetic field for compensation added to the longitudinal bias magnetic field when the longitudinal bias magnetic field was changed. It is the graph which put together FIG. 19 into one. It is a graph which shows the difference of the difference resistance value sensitivity with and without the temperature compensation function when the longitudinal bias magnetic field is 40 Oe.

(Embodiment 1)
First, the principle of temperature compensation according to the present embodiment will be described. FIG. 1 shows a circuit 1 in which metal A (3) and metal B (4) are connected in series, and a power source 2 is connected to the open ends of metal A (3) and metal B (4). An output end 5 is formed at a connection point between the metal A (3) and the metal B (4). Here, the metal A (3) is assumed to be a nonmagnetic metal such as copper, and the metal B (4) is assumed to be a magnetic metal having a magnetoresistance effect. Metal A (3) and metal B (4) have temperature characteristics. That is, the electric resistance of the metal A (3) changes depending on the temperature, and the electric resistance and magnetoresistance effect of the metal B (4) changes depending on the temperature.

The voltage of the power supply 2 is V ₀ , the voltage of the output terminal 5 is V _out , the electric resistance of the metal A (3) is R _A , and the electric resistance of the metal B (4) is R _B. In addition, t is a temperature rise from the reference temperature t ₀ (a negative value is used in the case of a drop), α _A is the temperature coefficient of the electric resistance R _A of the metal A (3), and R _A0 is the electricity at the reference temperature t _0. Let α _{B be} the temperature coefficient of the electric resistance R _B of the metal B (4), and R _B0 be the electric resistance at the reference temperature t ₀ . The electrical resistance of the metal A (3) and the metal B (4) when the temperature is t ₀ + t is expressed by the equations (1) and (2). The reference temperature t ₀ can be any temperature, for example room temperature may be selected.

Further, the voltage _Vout at the output terminal 5 is expressed as shown in Equation (3).

Next, the magnetoresistance effect is examined. As is well known, when an external magnetic field H ₀ is applied to the magnetoresistive element, the electrical resistance of the magnetoresistive element changes. The amount of change in electrical resistance is ΔR _mr . The change in electrical resistance is proportional to the coefficient of magnetoresistance effect β. Further, the magnetoresistive effect itself has temperature characteristics. Therefore, the temperature characteristic of the magnetoresistive effect is β _B, and the magnetoresistive effect coefficient at the reference temperature t ₀ is β ₀ .

That is, the coefficient β of the magnetoresistance effect is expressed as β = β ₀ (1 + β _B t) using the magnetoresistance effect coefficient β _{0 at the} reference temperature t ₀ and the temperature coefficient β _B of the magnetoresistance effect. According to the above preparation, the change amount ΔR _mr of the electric resistance of the magnetoresistive element is expressed by the equation (4).

Note that the _{R B,} by substituting the expression (2).

Assuming that the current flowing through the circuit of FIG. 1 is I, the voltage change ΔV _mr at the output terminal 5 due to ΔR _mr is expressed as in equation (5).

Here, a condition under which ΔV _mr does not change is obtained. That is, if ΔV _mr = ΔVMR (ΔVMR is a constant value), equation (5) can be transformed into equation (6). Here, ΔVMR is an output voltage obtained from both ends of the magnetic body by the magnetoresistive effect.

Further, when H ₀ V ₀ on the right side is moved to the left side, equation (7) is obtained.

Since the external magnetic field H ₀ and the power supply voltage V ₀ are not related to temperature, the left side is a constant value. Therefore, if the left side is newly set as K, equation (7) can be transformed into equation (8).

Further, when R _A0 and R _B0 are collected on the left side, the formula (9) is finally obtained.

(9) is a metal A (3) when (nonmagnetic metal) and metal B (4) to (magnetic metal) is raised from the reference temperature _{t 0} by temperature t, so that the output terminal 5 voltage _{V out} does not change It represents the ratio of electrical resistance between the metal A (3) and the metal B (4). In other words, a non-magnetic metal A (3) having a temperature coefficient α _A with respect to electrical resistance and a magnetic metal B (4) having a temperature coefficient with respect to electrical resistance α _B and a temperature coefficient with respect to the magnetoresistance effect β _B By setting the electrical resistance at the reference temperature t ₀ to be R _A0 and R _B0 , fluctuations in the output terminal voltage due to temperature can be reduced.

It should be noted that the accuracy of practical temperature compensation is preferably 10%, more preferably 7%, and most preferably within 5%. Therefore, it can be said that the relationship of the formula (9) is satisfied if the ratio is within 10% from the ratio obtained by the formula (9).

The ratio of the electrical resistance at the reference temperature t ₀ of the metal A (3) and the metal B (4) according to the equation (9) is the electrical resistance that increases in resistance value due to temperature rise and the magnetoresistance effect that decreases as the temperature rises. It is a ratio that can be made to cancel each other. Accordingly, the dynamic range set at the reference temperature t ₀ does not change apparently due to a temperature change.

More specifically, when the temperature moves in the direction in which the dynamic range of the output voltage _Vout due to the magnetoresistive effect increases, the electrical resistance in the circuit 1 increases, and when the temperature moves in the direction in which the dynamic range decreases, the electrical resistance Decrease. As a result, the dynamic range does not seem to change. In other words, by setting the ratio, such as (9) at a reference temperature t ₀ the electrical resistance of the metal A (3) and metal B (4), even if the temperature changes, automatically temperature compensated Is done.

FIG. 2A shows a configuration example of a magnetic sensor element to which the above temperature compensation principle is applied. A temperature-compensated magnetic sensor element (hereinafter, also simply referred to as “magnetic sensor element”) 10 includes a sensor unit 11 and a compensation metal unit 20. The sensor unit 11 is composed of a strip-shaped magnetic film 12. Of course, the magnetic film 12 is included in the magnetic material. Electrodes 11a and 11b are formed at both ends. This is the direction of the current I flowing from the electrode 11 a to the electrode 11 b through the magnetic film 12. The direction from the electrode 11a to the electrode 11b is referred to as the axial direction.

In the magnetic film 12, the direction of the magnetization 12M in the magnetic film 12 is tilted by the external magnetic field H having a component perpendicular to the direction in which the current flows (component perpendicular to the axial direction). It is considered that the magnetoresistive effect is expressed by the inclination between the direction of the magnetization 12M and the direction of the flowing current I. The magnetization 12M may be spontaneous magnetization or induced magnetization. Here, the description is continued as spontaneous magnetization.

FIG. 2B shows a graph showing the relationship between the external magnetic field H and the magnetoresistive effect. The vertical axis represents the electric resistance value R _mr of the magnetic film 12, and the horizontal axis represents the external magnetic field H. The external magnetic field H is positive when a magnetic field is applied from the left side to the right side in FIG. 2A (there is an S pole on the left side and an N pole on the right side). Referring to FIG. 2B, the magnetoresistive effect does not depend on the direction of the applied external magnetic field H. That is, with respect to the externally applied magnetic field H, the magnetoresistance effect (change in electrical resistance) is an even function.

Also, the linearity is not high when the external magnetic field H is near zero. Therefore, it is a common practice to apply a bias magnetic field H _bias in a direction perpendicular to the axial direction of the magnetic film 12 and use a portion with higher linearity. This is called a transverse bias magnetic field _Hbias . The resistance value R _m0 of the magnetic film 12 when the lateral bias magnetic field H _bias is applied is called an operating point. Several methods can be considered for applying the lateral bias magnetic field _Hbias . Here, an example in which a conductor film 13a having a pattern called a barber pole is provided on the surface of the magnetic film 12 with a conductor film 13a will be described.

FIG. 2 (c) shows a partially enlarged view of FIG. 2 (a). In the inclined conductor film 13a formed on the surface of the magnetic film 12, electrons run the shortest distance in the conductor film 13a. That is, electrons run in the width direction of the inclined conductor film 13a. On the other hand, the spontaneous magnetization 12M is generated in both end directions of the strip-shaped magnetic film 12. That is, since no external magnetic field H is present, the direction of the flowing current I and the magnetization 12M is inclined by the angle θ.

That is, even if a lateral bias magnetic field is not applied from the outside, the same effect as the lateral bias magnetic field H _bias is applied. In this specification, the apparent lateral bias magnetic field H _bias is applied not only by means for applying the lateral bias magnetic field H _bias to the magnetic film 12 from the outside with a magnet or an electromagnet, but also by the structure of the film constituting the sensor unit 11 in this way. Even in such a state, it is referred to as lateral bias magnetic field adding means 13. That is, the lateral bias magnetic field applying means 13 includes a magnet, an electromagnet, and a film structure that constitutes the sensor unit 11.

The compensation metal part 20 may be the same metal as the conductor film 13a or may be another metal. The compensation metal portion 20 may be said to be a temperature compensation metal. The ninety-nine fold shape is used to increase electrical resistance in a small space. A connection point between the sensor unit 11 and the compensation metal unit 20 is an output terminal 30. It is desirable that the temperature coefficient of the compensation metal portion 20 has the same order and opposite characteristics as the temperature characteristics of the magnetoresistive effect by the magnetic film 12. This is because it becomes easy to cancel the temperature characteristic of the magnetoresistive effect.

The magnetic sensor element 10 according to the present invention having such a configuration includes an open end (end portion not connected to the sensor portion 11) 20a of the compensating metal portion 20 and an open end side electrode of the sensor portion 11. A power source is connected to 11b and a current flows. When an external magnetic field H having a magnetic field component perpendicular to the axial direction of the sensor unit 11 is applied, the output voltage of the output terminal 30 of the magnetic sensor element 10 changes. By measuring this voltage change, the magnitude of the external magnetic field H can be detected.

Further, by configuring the electrical resistance in the compensation metal part 20 and the electrical resistance of the sensor part 11 as R _A and R _{B so} as to satisfy the relationship of the expression (9), the magnetic sensor element 10 Appears to be automatically temperature compensated, and the dynamic range of the output terminal 30 is prevented from changing due to the external temperature.

(Embodiment 2)
Next, a power measuring apparatus using the magnetic sensor element 10 according to the present invention will be described with reference to FIG. The power and power factor consumed by the load of the power supply circuit can be obtained by using the magnetic sensor element 10 (see Patent Document 1). The operation principle of the power measuring apparatus using the magnetic sensor element 10 will be briefly described.

First, referring to FIG. 3, the power measuring device 6 according to the present invention is connected in parallel with the load 92 with respect to a circuit in which the load 92 is connected to the power source 91. The power measuring device 6 includes connection terminals 22a and 22b, a magnetic sensor element 10, a measurement resistor 24, and a detection means 27. The detection means 27 includes a differential amplifier 25 and uses the electrodes 11a and 11b of the sensor unit 11 as measurement terminals. The measurement terminal is connected to the terminal of the differential amplifier 25.

The magnetic sensor element 10 is the magnetic sensor element 10 having the barber pole type sensor unit 11 and the compensating metal unit 20 described in FIG. That is, the lateral bias magnetic field applying means 13 by the conductor film 13a is applied. The magnetic sensor element 10 and the measurement resistor 24 are connected in series and connected in parallel with a load 92 connected to the power source 91 of the circuit under measurement 90.

The connecting points are connection terminals 22a and 22b. The magnetic sensor element 10 is arranged adjacent to and parallel to the electric wire 93a connecting the power source 91 and the load 92. Here, “parallel” means that the in-plane direction of the magnetic film 12 is parallel to the coaxial magnetic field H formed around the electric wire 93a.

The in-plane direction is a direction perpendicular to the axial direction of the magnetic sensor element 10. This is because the magnetization 12M is inclined with respect to the external magnetic field H in this direction, and a magnetoresistive effect is exhibited. Further, the measurement resistor 24 is assumed to be sufficiently larger than the resistance value R _mr of the magnetic film 12 in the magnetic sensor element 10. This is because a constant current is supplied to the magnetic sensor element 10. Further, it is assumed that the resistance of the electric wire 93a is sufficiently small.

First, when the power supply 91 is a direct current, and the current flowing through the electric wire 93a, to 93b and I _1, the external magnetic field H applied to the magnetic sensor element 10, as a proportionality constant alpha, is expressed as equation (21) The
H = αI ₁ (21)

As shown in FIG. 2B, since the change ΔR _mr of the electric resistance of the magnetic film 12 is proportional to the external magnetic field H, when the proportionality constant is β and the equation (21) is considered, the equation (22) It is expressed as
ΔR _mr = βH = β (αI ₁ ) (22)

When the electric resistance when the external magnetic field H is not applied to the magnetic film 12 (operating point) is R _m0 , the electric resistance R _mr of the magnetic film 12 when the external magnetic field H is applied is It is expressed as follows.
R _mr = R _m0 + ΔR _mr = R _m0 + αβI ₁ (23)

That is, the magnetic film 12 which is disposed close to the electric wire 93a of the current I ₁ flows, has an electrical resistivity characteristics, such as (23). When the current I ₂ flows between the electrodes 11a and 11b of the magnetic film 12, the voltage V _mr between the electrodes 11a and 11b is expressed by the equation (24).
V _mr = R _mr I ₂ = (R _m0 + ΔR _mr ) I ₂ = (R _m0 + αβI ₁ ) I ₂ (24)

Then since the power source 91 is a DC if the voltage _{V in} and _{V 1,} are expressed as (25). The resistances of the electric wires 93a and 93b are sufficiently small, and the electric resistance R _mr of the magnetic film 12 is also sufficiently smaller than the measurement resistance 24 (value is R ₂ ). Assuming that the resistance of the load 92 is R ₁ , the current I ₁ flowing through the electric wire 93 a and the current I ₂ flowing through the magnetic film 12 are expressed by the equations (26) and (27), respectively.

Therefore, the voltage V _mr between the electrodes 11a and 11b of the magnetic film 12 is expressed by the equation (28). In addition, the relationship of R _m0 << R ₂ was used in the middle of the equation modification of the equation (28). The _{K 1} is a proportionality constant. From the result of the equation (28), between the electrodes 11a and 11b of the magnetic film 12, the voltage proportional to the electric power I ₁ V ₁ consumed by the load 92, the operating point of the measuring resistor 24 (R ₂ ), and the magnetic film 12 are obtained. When the electric resistance R _m0 in (see FIG. 2B) is determined, a uniquely determined bias voltage sum can be obtained.

Such a relationship is established even when the power source 91 is AC. Next, the case where the power source 91 is alternating current and the load 92 is reactance will be described. The relationship between the equations (21) to (24) is as described above. Since the power supply 91 is an AC voltage _{V in,} the amplitude _{V 1,} when the angular frequency omega, is expressed by the equation (29). Further, since the load 92 in the measuring circuit 90 is reactance current _{I 1} flowing through the load 92, the phase shift occurs between the power supply 91 (voltage _{V in).} Let this phase shift be θ. On the other hand, the magnetic film 12 is _{in the} same phase as the power source 91 (voltage V _in ) because it is a normal electric resistance (no phase shift). Therefore, the currents I ₁ and I ₂ are expressed as in the equations (30) and (31).

Therefore, if the expressions (30) and (31) are substituted into the expression (24), the expression (32) is transformed.

Looking at equation (32), it can be seen that the last term shows the active power consumed by the load 92 as a DC component. That is, the DC voltage obtained by passing the output between the measurement terminals 11 a and 11 b through the low-pass filter is proportional to the effective power consumed by the load 92. As described above, by using the magnetic film 12, not only the current flowing through the electric wires 93a and 93b but also the power consumption at the load 92 connected to the power source 91 can be measured by the connection method.

As described above, in the configuration of FIG. 3, regardless of whether the power source 91 is a direct current or an alternating current, the power consumed by the load 92 connected to the power source 91 can be taken out as a voltage. A means for detecting the voltage between the electrodes (measurement terminals) 11a and 11b of the magnetic film 12 and detecting a voltage proportional to the power consumption of the load 92, excluding the DC bias component and the AC component, is referred to as a detecting means 27. The detection unit 27 includes a differential amplifier 25 and a post-processing unit 26.

The post-processing means 26 is means for removing AC and DC bias voltages superimposed on the output of the differential amplifier 25. Specifically, when AC is superimposed, it is a low-pass filter, and when DC bias voltage is superimposed, it is a means for applying a voltage having the same absolute value but the opposite polarity. Or a battery.

The power measuring device 6 according to the present invention is equipped with the magnetic sensor element 10 shown in the first embodiment. An example of how to design the magnetic sensor element 10 is shown. The assumed temperature range in the environment where the power measuring device 6 is used is determined. Next, a metal material having linearity is selected in this temperature range. Note that the power measuring device 6 uses the measuring resistor 24 included in the power measuring device 6 itself, not the load 92 in the circuit under measurement 90. For the metal material, the material of the measuring resistor 24 is also considered.

Next, the temperature characteristics (particularly the temperature coefficient) of these metal materials are obtained. This may be confirmed by a commercially available data table or the like, but it should be confirmed by experiments in a state where it is actually used. This corresponds to _{obtaining the} temperature coefficient α _A and the electric resistance R _A0 at the reference temperature t ₀ in the metal A (3) described above.

Next, a magnetic metal having a magnetoresistance effect is selected. In this case, it is desirable that the electric resistance and the magnetoresistance effect vary as little as possible in the temperature range to be used. The temperature coefficient α _B of the electric resistance and the temperature coefficient β _B of the magnetoresistance effect of the selected magnetic metal are obtained. Next, these values are applied to the equation (9), and the electric resistance value R at the reference temperature t ₀ of the metal A (3) (nonmagnetic metal) and the metal B (4) (magnetic metal) at the reference temperature t ₀ . The ratio of _A0 and R _B0 is obtained.

The size of the magnetic film 12 is determined from the current flowing through the circuit to be detected, the space where it can be installed, and the like. If the size of the magnetic film 12 is determined, the electric resistance value R _B0 of the magnetic film 12 at the reference temperature t ₀ is determined, and the electric resistance value R _{A0 of the} conductor film 13a at the reference temperature t ₀ is also determined from the relationship of the equation (9). Can be determined.

If the electric resistance value _RA0 of the conductor film 13a is determined, the shape of the conductor film 13a having the electric resistance value can be determined. In this way, it is possible to form the magnetic sensor element 10 that is in proportion to the electrical resistance at the reference temperature shown in the equation (9).

(Embodiment 3)
In the first and second embodiments, the temperature dependence of the magnetoresistive effect appearing at the junction between the nonmagnetic metal and the magnetic metal is canceled by connecting in series the nonmagnetic metal and the magnetic metal having different temperature characteristics regarding resistance. It was shown that you can.

The principle is that when the temperature rises and the magnetoresistance effect of the magnetic metal decreases, the resistance value of the nonmagnetic metal decreases. Therefore, it can be realized by using an element whose electric resistance value decreases as the temperature rises.

In Embodiments 1 and 2, this is shown as a temperature compensating metal (compensating metal portion 20). However, the element is not limited to metal as long as the electric resistance value decreases as the temperature increases. For example, an active element such as an IC may be used. In this sense, in this specification, the temperature compensating metal may include an active element and a circuit using the active element.

In this embodiment, an example is shown in which an NTC (Negative Temperature Coefficient) thermistor is used as an element whose resistance value decreases as the temperature rises. The NTC thermistor is a temperature compensating metal.

The NTC thermistor is manufactured by mixing and sintering oxides such as nickel, manganese, cobalt, and iron. FIG. 4 shows the relationship between the resistance _{R NTC} and the temperature of the NTC thermistor. Referring to FIG. 4, the horizontal axis represents temperature (° C.), and the vertical axis represents resistance value R _NTC (Ω). The resistance value of the NTC thermistor decreases exponentially with increasing temperature.

When NTC thermistor is connected in parallel with the resistor, it is possible to obtain a characteristic of a resistance value close to linear with respect to temperature. FIG. 5 shows a configuration of a magnetic sensor element 32 having an autonomous temperature compensation function using an NTC thermistor. The magnetic sensor element includes an adjustment resistor 33 (resistance value R), a compensation resistor 34, and a sensor unit 36. The connection order of the adjustment resistor 33 and the compensation resistor 34 may be reversed. Here, the description will be continued assuming that the adjustment resistor 33 is disposed closer to the power source 38. The power source 38 may be a current source.

The compensation resistor 34 is configured by connecting a resistor 34r and an NTC thermistor 34s in parallel. A desired temperature characteristic can be obtained by changing the resistance value and type of the adjustment resistor 33, the compensation resistor 34r, and the NTC thermistor 34s. The adjustment of the temperature characteristic of the compensation resistor 34 will be described in more detail in the fourth embodiment.

The connection point between the sensor unit 36 and the compensation resistor 34 is the output terminal 30 of the magnetic sensor element 32. The sensor unit 36 may have the same configuration as the sensor unit 11 of the first and second embodiments. That is, it is composed of a magnetoresistive effect element having the magnetic film 12 and the lateral bias magnetic field applying means 13.

The magnetic sensor element 32 applies a voltage between the terminal of the adjustment resistor 33 and the sensor unit 36, and external magnetic fields from the lateral direction of the sensor unit 36 (perpendicular to the longitudinal direction (axial direction) of the strip shape). Is applied, a voltage change corresponding to the external magnetic field can be obtained at the output terminal 30.

When the temperature of the entire magnetic sensor element 32 rises, the resistance value of the combined resistance by the adjusting resistor 33 and the compensation resistor 34 decreases as the temperature increases. Then, the voltage applied to both ends of the sensor unit 36 increases. Although the magnetoresistive effect decreases as the temperature rises, the voltage applied to the sensor unit 36 increases, so that the voltage change due to the magnetoresistive effect observed at both ends of the sensor unit 36 increases. A change in output at the output terminal 30 can be canceled by a decrease in the magnetoresistive effect and an increase in the voltage applied to the sensor unit 36. That is, the output dynamic range is compensated.

At this time, the combined resistance value of the adjustment resistor 33 and the compensation resistor 34 and the resistance value of the sensor unit 36 are in a ratio expressed by the equation (9). Note that the ratio expressed by the formula (9) is preferably 10% or less, more preferably 7% or less, and most preferably 5% or less with respect to the ratio of the formula (9). This is the same as in the first embodiment. Further, the magnetic sensor element 32 of FIG. 5 can be used in place of the magnetic sensor element 10 of the power measuring device 6 shown in FIG. 3, and also has an amplifier and a current source for amplifying the output voltage. , Magnetic sensor. It can also be used as a current measuring device and a power factor measuring device.

In the magnetic sensor element 32 according to the present embodiment, it is sufficient that the compensation resistor 34 and the sensor unit 36 are connected in series. The adjustment resistor 33 is connected in order to perform compensation with higher accuracy. Even without the adjustment resistor 33, the magnetic sensor element 32 has a temperature compensation function.

(Embodiment 4)
In the present embodiment, two magnetic sensor elements 32 shown in the third embodiment are used in parallel to form a bridge circuit. By using a bridge circuit, the gain of the entire magnetic sensor element can be doubled with respect to an externally applied magnetic field.

FIG. 6A shows a magnetic sensor element 40 according to the present embodiment. The magnetic sensor element 40 is formed by a bridge circuit including a first sensor unit 41, a second sensor unit 42, a first bridge resistor 43, a second bridge resistor 44, a first compensation resistor 45, and a second compensation resistor 46. The first bridge resistor 43, the first compensation resistor 45, and the first sensor unit 41 are connected in series. Further, the second bridge resistor 44, the second compensation resistor 46, and the second sensor unit 42 are connected in series.

FIG. 6B shows a magnetic sensor in which the first bridge resistor 43 and the first compensation resistor 45 are replaced with the first bridge resistor 51, and the second bridge resistor 44 and the second compensation resistor 46 are replaced with the second bridge resistor 52. Element 50 is shown. It can be said that the magnetic sensor element 40 is obtained by adding a temperature compensation function to the magnetic sensor element 50.

Referring to FIG. 6A, the terminals of the first bridge resistor 43 and the second bridge resistor 44 are connected to each other to form a magnetic sensor terminal 40a. Further, the terminals of the first sensor unit 41 and the second sensor unit 42 are also connected to form a magnetic sensor terminal 40b. The connection relationship between the first bridge resistor 43 and the first compensation resistor 45 may be reversed. Similarly, the connection relationship between the second bridge resistor 44 and the second compensation resistor 46 may be reversed. Here, the terminals of the first bridge resistor 43 and the second bridge resistor 44 are connected to each other, and the first compensation resistor 45 and the second compensation resistor 46 are connected to the first sensor unit 41 and the second sensor unit 42, respectively. Continue to explain.

The first compensation resistor 45 and the second compensation resistor 46 are resistors configured by connecting a resistor and an NTC thermistor in parallel. That is, the first compensation resistor 45 is configured by a parallel connection of a resistor 45r and an NTC thermistor 45s, and the second compensation resistor 46 is configured by a parallel connection of a resistor 46r and an NTC thermistor 46s. The NTC thermistor has been described in the third embodiment. Of course, the NTC thermistor is a temperature compensating metal.

The output of the magnetic sensor element 40 is a voltage between a connection point 47 between the first compensation resistor 45 and the first sensor unit 41 and a connection point 48 between the second compensation resistor 46 and the second sensor unit 42. The voltages at the respective connection points are V47 and V48.

The first sensor unit 41 and the second sensor unit 42 may be the sensor unit 11 described in the first and second embodiments. In other words, it is a strip-shaped product made of the magnetic film 12 provided with the lateral bias magnetic field applying means 13. However, in the first sensor unit 41 and the second sensor unit 42, the direction of the lateral bias magnetic field applying unit 13 is opposite. By doing so, voltage changes at the connection points 47 and 48 occur in the reverse direction, and by differentially amplifying this, the output gain can be doubled.

In FIG. 6, the formation direction of the conductor film 13a is reversed between the first sensor portion 41 and the second sensor portion. That is, a state in which the direction of the lateral bias magnetic field applied in a direction perpendicular to the longitudinal direction of the strip-shaped magnetic film 12 is reversed between the first sensor unit 41 and the second sensor unit 42 is shown.

In addition, the 1st sensor part 41 and the 2nd sensor part 42 may be the arrow feather pattern shown in FIG. 7 instead of the BBP pattern shown in FIG.

FIG. 7A shows only the first sensor unit 41. The second sensor unit 42 is a symmetrical pattern of the first sensor unit 41. Referring to FIG. 7A, the first sensor portion 41 is formed with a plurality of strip-like magnetic films 12m inclined by an angle θ with respect to the longitudinal direction of the strip-like substrate. And the edge part of the adjacent strip | belt-shaped magnetic film 12m is connected by the connection part 12j every other line. As a result, the plurality of strip-like magnetic films 12m become one strip-like magnetic film. In addition, electrodes 41 a and 41 b of the first sensor unit 41 are formed at both ends of one strip-shaped magnetic film.

7B, the second sensor unit 42 has a pattern of a strip-shaped magnetic film 12m that is symmetrical to the first sensor unit 41. In addition, one electrode 41b of the first sensor unit 41 and one electrode 42b of the second sensor unit 42 are connected. In the state of FIG. 7B, the pattern of the magnetic film 12m of the first sensor unit 41 and the second sensor unit 42 resembles an arrow feather, which is called an arrow feather pattern. The arrow feather pattern applies a bias magnetic field in the direction AA in which the connecting portions 12j are arranged. This bias magnetic field is called a longitudinal bias magnetic field.

The magnetization of the magnetic film 12m is aligned in the direction of the bias magnetic field by the longitudinal bias magnetic field. The magnetic film 12m is inclined by an angle θ with respect to the bias magnetic field. Therefore, since the magnetization and the direction of the flowing current are different, it seems that a lateral bias magnetic field is apparently applied. That is, applying a longitudinal bias magnetic field to the arrow feather pattern is equivalent to applying a lateral bias magnetic field depending on the structural characteristics of the magnetic film. Therefore, it can be said that the vertical bias magnetic field applied to the arrow feather pattern has the lateral bias magnetic field adding means 13.

In addition, the inclination direction of the magnetic film 12m of the first sensor unit 41 and the second sensor unit 42 is opposite to the longitudinal bias magnetic field. Therefore, in the case of the arrow feather pattern of FIG. 7B, it can be said that the lateral bias magnetic field adding means 13 is provided in the reverse direction.

Refer to FIG. 6 again. The operating principle of the magnetic sensor element 40 is the same as that described in the first to third embodiments. That is, when the temperature rises, the magnetoresistive effect of the first sensor unit 41 and the second sensor unit 42 decreases. However, the combined resistance of the first bridge resistor 43 and the first compensation resistor 45 and the combined resistance of the second bridge resistor 44 and the second compensation resistor 46 are decreased. Therefore, the voltage applied to the first sensor unit 41 and the second sensor unit 42 increases, and the output voltage between the first sensor unit 41 and the second sensor unit 42 does not change. Therefore, the output is also temperature compensated.

A detailed description of temperature compensation is given below. First, description will be made using the magnetic sensor element 50 of FIG. The output of the magnetic sensor element 50 is represented by V48-V49.

The magnetic sensor terminals 50a, the voltage applied between 50b was _{V in.} The resistance values of the first bridge resistor 51 and the second bridge resistor 52 are R, and the resistance values of the first sensor unit 41 and the second sensor unit 42 are R _mr . A change in resistance value due to the magnetoresistive effect is represented by ΔR. This is the same for the first sensor unit 41 and the second sensor unit 42.

Looking at the first equation of equation (33), there are terms where ΔR is positive and negative. This is because the lateral bias magnetic field applying means 13 of the first sensor unit 41 and the second sensor unit 42 is provided in the opposite direction.

Here, R = αR _mr and V48−V49 = V (α). This is intended to control the magnitude of the output V (α) by changing the first bridge resistor 51 and the second bridge resistor 52.

When the coefficient portion 2α / (1 + α) ^{2 in} the equation (34) is set to Gain (bridge gain), the relationship between α and Gain is as shown in FIG. Gain has an extreme value when α = 1. That is, when R = R _mr , the output of the bridge circuit is maximized. In the present invention, this α is regarded as a coefficient depending on temperature, and compensation is performed. As will be described later, temperature compensation is performed on the assumption that α can be linearly approximated within a range of 1 ≦ α ≦ 4.

In the equation (34), R _mr is the resistance value of the magnetic film of the first sensor unit 41 and the second sensor unit 42. 2ΔR corresponds to the resistance sensitivity obtained from the graph of the magnetoresistance effect obtained by subtracting the temperature characteristics of the resistance values of the first sensor unit 41 and the second sensor unit 42, respectively. In addition, about resistance value sensitivity, Embodiment 5 illustrates a measured value and a measuring method. When actually measured, these variables have characteristics that are very linear with respect to temperature. Therefore, these are linearly approximated.

　なお、ここで「ｔ」は温度を表す。ａ_１、ａ_２、ｂ_１、ｂ_２は、第１センサ部４１および第２センサ部４２を実際に温度環境で測定し求める係数である。

Here, “t” represents temperature. a ₁ , a ₂ , b ₁ and b ₂ are coefficients obtained by actually measuring the first sensor unit 41 and the second sensor unit 42 in a temperature environment.

Also, assuming that all variables are linear, the output V ′ _{(α, t)} per unit magnetic field can be obtained by substituting Equation (35) and Equation (36) into Equation (34) as follows: expressed.

V ′ _{(α, t)} is an output voltage per unit magnetic field (external magnetic field) of the magnetic sensor element 50 when α and temperature t are determined. If the output is regarded as an output per unit magnetic field, ΔR can be a resistance sensitivity (Ω / Oe). Here the temperature t and the upper limit of the temperature of the temperature compensation range, when determining the coefficient α to a number between 1 and 4, (37) where the coefficient of V _in the right side can be determined specifically. This is because a ₁ , a ₂ , b ₁ , and b ₂ are specifically obtained from actually measured values. This is k ₀ . That is, equation (38).

　また、（３７）式左辺をＶ’（α）と置くと、（３８）式を考慮して、（３９）式が成り立つ。

Further, when the left side of the expression (37) is set as V ′ (α), the expression (39) is established in consideration of the expression (38).

　ｋ_１およびｋ_２は、図８のグラフにおいて、１≦α≦４の範囲でαを線形近似した時の傾きおよび切片である。 As shown in FIG. 8, when α is linearly approximated within the range of 1 ≦ α ≦ 4, the equation (39) is expressed as the following equation (40).

k ₁ and k ₂ are the slope and intercept when α is linearly approximated in the range of 1 ≦ α ≦ 4 in the graph of FIG.

When α is obtained from the equations (39) and (40), the equation (41) is obtained.

Substituting the formulas (35) and (36) into R _mr and 2ΔR in the formula (41) gives the formula (42).

In the first place, since R = αR _mr , the resistance value R of the first bridge resistor 51 (the same applies to the second bridge resistor 52) is expressed as follows.

This equation represents a condition for the output of the magnetic sensor element 50 not to change with temperature if the first bridge resistor 51 and the second bridge resistor 52 follow the temperature characteristics of the equation (43).

The following shows a specific measurement example and shows that temperature compensation along these formulas can be realized.

FIGS. 9A and 9B show the temperature characteristics of the resistance value and the resistance sensitivity of the actually produced first sensor part 41 (the same applies to the second sensor part 42). In FIG. 9A, the horizontal axis represents temperature (° C.), and the vertical axis represents resistance value (Ω). In FIG. 9B, the horizontal axis represents temperature (° C.), and the vertical axis represents differential resistance sensitivity (Ω / Oe). From these graphs, the coefficients of the equations (35) and (36) can be read as follows. a ₁ = 18.23 [Ω / ° C.], b ₁ = 5286 [Ω], a ₂ = −0.01295 [Ω / Oe], b ₂ = 9.933 [Ω / ° C.].

These values are substituted into equation (37). When the upper limit of the temperature compensation range is 100 ° C. and α is 1, k ₀ = 3.038 × 10 ⁻⁴ . Further, from FIG. 8, when the bridge gain is linearly approximated within the range of 1 ≦ α ≦ 4, the slope (k ₁ ) = − 2.213 and the intercept (k ₂ ) = 0.2948.

If this is substituted into the equation (43) to make a graph, FIG. 10 is obtained. Referring to FIG. 10, the horizontal axis represents temperature (° C.), and the vertical axis represents the resistance value (Ω) of the first bridge resistor 51 (the same applies to the second bridge resistor 52). That is, if the first bridge resistance 51 and the second bridge resistance 52 have the characteristics shown in FIG. 10 with respect to the first sensor section 41 and the second sensor section 42 having the characteristics shown in FIG. It becomes. The output is compensated for temperature.

A specific method for the first bridge resistor 51 (second bridge resistor 52) to exhibit the characteristics of FIG. 10 is as shown in FIG. 6A, instead of the first bridge resistor 51, the first bridge resistor 43. And the first compensation resistor 45 is used. The first compensation resistor 45 is formed by connecting a resistor 45r and an NTC thermistor 45s in parallel. The second compensation resistor 46 is formed by connecting a resistor 46r and an NTC thermistor 46s in parallel.

FIG. 11 shows the temperature characteristics of the first compensation resistor 45 when the NTC thermistor 45s is 100 kΩ and the resistor 45r is 0, 5k, 10k, 20k, 30k, 40k, 50k, 60k, 70k, 80k, 90, 100kΩ. The graph of is shown. 11A shows the case of 0 to 50 kΩ, and FIG. 11B shows the case of 60 to 100 kΩ. The horizontal axis represents temperature, and the vertical axis represents normalized resistance (standardized resistance: no unit). The normalized resistance is a value obtained by dividing the resistance value at each temperature by the maximum resistance value of the first compensation resistor 45 in the case of a combination of a certain value of the resistor 45r and the NTC thermistor 45s.

Referring to FIG. 11A, when the resistance 45r is zero Ω, the temperature characteristic of the NTC thermistor 45s appears as it is, and the resistance value decreases exponentially as the temperature increases. However, as the value of the resistor 45r increases, the resistance value of the first compensation resistor 45 changes smoothly with respect to temperature.

Referring to FIG. 11B, when the resistance value of the resistor 45r becomes larger than half of the resistance value of the NTC thermistor 45s (here, 100 kΩ), the value of the first compensation resistor 45 converges to a shape close to linear. Looks like.

FIG. 12 shows the temperature dependence of the first compensation resistor 45 when the resistor 45r is fixed to 10 kΩ and the resistance value of the NTC thermistor 45s is changed to 100 kΩ, 220 kΩ, and 470 kΩ. Referring to FIG. 12, the horizontal axis represents temperature (° C.), and the vertical axis represents normalized resistance value (no unit). As the resistance of the NTC thermistor 45s increases, the temperature dependence decreases.

Thus, the temperature characteristics of the first compensation resistor 45 can be adjusted by adjusting the resistance values of the resistor 45r of the first compensation resistor 45 and the NTC thermistor 45s. Furthermore, by adjusting the resistance value of the first bridge resistor 43 connected in series to the first compensation resistor 45, a temperature characteristic very close to that in FIG. 10 can be realized. The same applies to the second compensation resistor 46.

In order to actually match the characteristics of FIG. 10, the parameters were adjusted as follows. In FIG. 10, since the resistance value at −10 ° C. was 20982 [Ω], the resistor 45r was connected in parallel with 20 kΩ and the NTC thermistor 45 s was 220 kΩ, and the first bridge resistor 43 was set at 1 kΩ. FIG. 13 shows the actually measured value of the temperature dependency of the resistor thus manufactured and the value of FIG. The value shown in FIG. 10 is indicated as the necessary resistance in FIG. In FIG. 13, the horizontal axis represents temperature (° C.) and the vertical axis represents resistance (Ω).

Referring to FIG. 13, the combined resistance of the first bridge resistor 43 and the first compensation resistor 45, the temperature characteristics of which have been adjusted as described above, was very close to the calculation result of FIG. In FIG. 13, the circles and solid lines that are necessary characteristics are the lines obtained in FIG. 10. Compensation resistance is a square mark and a chain line. The above description can be similarly applied to the second bridge resistor 44 and the second compensation resistor 46.

As described above, the temperature characteristics of the magnetic sensor element 40 having the temperature compensation function and the magnetic sensor element 50 having no temperature compensation function were simulated. The magnetic sensor element 50 was set so that the resistance values of the first bridge resistor 51 and the first sensor unit 41 were the same at room temperature. The second bridge resistor 52 and the second sensor unit 42 have the same resistance value at room temperature.

Fig. 14 shows the simulation results. The horizontal axis represents temperature (° C.), and the vertical axis represents the change (%) in the output of each magnetic sensor element 40, 50. Circle marks indicate after compensation, square marks indicate before compensation, and dotted lines indicate ideal outputs. The ideal output is an output when the output does not depend on temperature. With the output at 25 ° C. in the range of −10 ° C. to 100 ° C. as the reference (zero), the magnetic sensor element 50 (without the temperature compensation function) produces an output change of 45.6% with respect to the ideal output. On the other hand, in the magnetic sensor element 40 (with a temperature compensation function), output fluctuation can be suppressed to a change of 5.7% with respect to the ideal output.

In the present invention, if the first compensation resistor 45 (second compensation resistor 46) includes a configuration in which an NTC thermistor and a resistor are connected in parallel, there is no particular limitation on the configuration for performing temperature compensation. Therefore, the output fluctuation in FIG. 14 can be further reduced by performing more detailed adjustment. It is considered that the output fluctuation with respect to the temperature that can be practically used as a magnetic sensor element is preferably 10% or less, more preferably 7% or less, and most preferably 5% or less. Therefore, the first bridge resistor 43 and the first compensation resistor 45 (the second bridge resistor 44 and the second compensation resistor 46 are also set so as to be within 10% from the characteristic of the resistance required for the temperature compensation obtained in FIG. If the same is adjusted, it can be said that the present invention has been implemented.

The magnetic sensor element 40 according to the present embodiment can be used in the power measuring device 6 shown in FIG. 3 as well as the amplifier and the current source for amplifying the output voltage. It can also be used as a rate measuring device. Also in the magnetic sensor element 40 according to the present embodiment, it is sufficient that the first compensation resistor 45 and the first sensor unit 41 and the second compensation resistor 46 and the second sensor unit 42 are connected in series. The first bridge resistor 43 and the second bridge resistor 44 are connected in order to perform compensation with higher accuracy, and the magnetic sensor element 40 has a temperature compensation function even if these are not necessary.

(Embodiment 5)
In the present embodiment, an invention for compensating temperature compensation by the magnitude of the longitudinal bias magnetic field will be described. FIG. 15 shows the configuration of the magnetic sensor element 60 according to the present embodiment. The magnetic sensor element 60 can include a sensor unit 61, a longitudinal bias magnetic field generator 62, a battery 63, a magnetic field sensor 64, a thermometer 65, a current regulator 66, and a controller 70.

As the sensor unit 61, the one described in the first to fourth embodiments can be used. FIG. 15 illustrates the arrow feather pattern shown in FIG. However, the conductor film 13a may be provided with a BBP pattern.

Here, the longitudinal bias magnetic field generator 62 is an electromagnet driven by a battery 63. However, as will be described later, it may be a permanent magnet capable of changing a predetermined longitudinal bias magnetic field with respect to a temperature change.

The differential amplifier 25 amplifies the voltage at both ends (between 61a and 61b) of the sensor unit 61. The thermometer 65 measures the temperature of the sensor unit 61. The temperature measured by the thermometer 65 is output as a signal St. The magnetic field sensor 64 measures the magnitude of the magnetic field generated by the longitudinal bias magnetic field generator 62. The measurement result is output as a signal Shb.

The controller 70 knows the temperature of the sensor unit 61 from the signal St from the thermometer 65, and adjusts the output voltage of the battery 63 with the control signal Cb so that a longitudinal bias magnetic field for compensation described later is generated. Here, the current regulator 66 is disposed between the battery 63 and the longitudinal bias magnetic field generator 62. However, the configuration is not limited to this configuration as long as the strength of the longitudinal bias magnetic field can be adjusted.

The magnitude of the longitudinal bias magnetic field is known from the signal Shb from the magnetic field sensor 64. Actually, a current supply source (not shown) is connected to both ends 61 a and 61 b of the sensor unit 61. An external magnetic field serving as a load is applied from a direction perpendicular to the direction of the longitudinal bias magnetic field.

Also, a pair of sensor units 61 may be prepared (sensor unit 62), and the difference between the two sensor units may be used as an output. FIG. 15B shows a rough configuration. One terminal of the first sensor unit 61 and the second sensor unit 67 is made common and grounded. The other ends of the first sensor unit 61 and the second sensor unit 67 are grouped together via a resistor. The combined portion and the ground terminal become the input terminal of the differential amplifier 25. The other ends of the first sensor unit 61 and the second sensor unit 67 are connected to current sources (not shown). An external magnetic field serving as a load is applied from a direction perpendicular to the longitudinal bias magnetic field.

FIG. 16A shows the result of measuring the magnetoresistive effect of the sensor unit 61 with different longitudinal bias magnetic fields. The horizontal axis is the external magnetic field (Oe). The portion where the sign is negative indicates that the direction of the magnetic field applied to the sensor unit 61 is reversed. Further, the measured value of the magnetoresistive effect of the second sensor unit 67 to which the lateral bias magnetic field is applied in the opposite direction to the lateral bias magnetic field adding unit 13 of the first sensor unit 61 is also shown. In these, the peaks and valleys of the characteristic curve are reversed with respect to the axis of zero external magnetic field. The slope at the point where the external magnetic field of the magnetoresistive effect is zero is the resistance sensitivity.

FIG. 16B is a result of subtracting the resistance values of the first sensor unit 61 and the second sensor unit 67 of FIG. 16A for each external magnetic field. This is the differential resistance value. That is, by using the resistance values of the first sensor unit 61 and the second sensor unit 67 so as to differ from each other, an output voltage obtained by multiplying the applied voltage by FIG. 16B can be obtained.

傾 き The slope of the differential resistance value when the external magnetic field is zero is the differential resistance sensitivity. As can be seen from FIG. 16B, when the longitudinal bias magnetic field increases, the linear area increases, but the resistance sensitivity decreases. In other words, in FIG. 16B, the slope of the characteristic curve at zero external magnetic field becomes small.

In FIG. 17, the horizontal axis represents the magnitude of the vertical bias magnetic field (Oe), and the vertical axis represents the measured value of the differential resistance value sensitivity (Ω / Oe). As the longitudinal bias magnetic field increases, the differential resistance sensitivity decreases exponentially. That is, when the temperature of the magnetic sensor element rises and the output voltage decreases, the differential resistance sensitivity increases and the output increases by reducing the longitudinal bias magnetic field. By canceling the decrease in output of the magnetoresistive effect and the increase in differential resistance sensitivity due to the decrease in the longitudinal bias magnetic field, temperature compensation becomes possible. Details will be described below.

As shown in FIG. 9B, the resistance sensitivity of the magnetoresistive effect decreases almost linearly with respect to temperature. Therefore, the resistance value sensitivity c of the sensor unit 61 is expressed as a formula (44) as a function of temperature.

Here, when the temperature of the sensor unit 61 changes to t + Δt, the sensitivity of the sensor unit 61 is expressed by the equation (45). The sensitivity of the sensor unit 61 may be considered resistance value sensitivity.

That is, when the temperature is changed from t to t + Delta] t, the magnification alpha ₁ of the resistance value sensitivity of the sensor unit 61 is expressed by the expression (46).

　ｃ_０、Ａ、βは実験値から得られる値である。 Next, since the resistance value sensitivity of the sensor unit 61 changes exponentially with respect to the longitudinal bias magnetic field Hb, it is expressed as in equation (47).

c ₀ , A, and β are values obtained from experimental values.

Here, assuming that the longitudinal bias magnetic field changes to Hb + ΔHb, the resistance value sensitivity of the sensor unit 61 is expressed by equation (48).

Therefore, when the longitudinal bias magnetic field changes from H to Hb + ΔHb, the resistance sensitivity α ₂ is expressed as shown in Equation (49).

From the above, if it is attempted to compensate for the change in sensitivity due to the temperature change with the longitudinal bias magnetic field, the following condition (50) must be satisfied.

The equation (46) and the equation (49) are substituted into the equation (50) for deformation.

Equation (51) indicates how much the longitudinal bias magnetic field should be changed when the temperature changes from t to t + Δt.

As shown in FIG. 17, when the longitudinal bias magnetic field changes, the differential resistance sensitivity changes exponentially. Therefore, it is conceivable that the degree of compensation of the temperature characteristics varies depending on the magnitude of the longitudinal bias magnetic field. In fact, when the temperature characteristics of the differential resistance value sensitivity of the first sensor unit 61 and the second sensor unit 67 having the measurement values of FIG. 16 are measured, the differential resistance value sensitivity differs depending on the magnitude of the longitudinal bias magnetic field.

Fig. 18 shows the measurement results. 18A shows differential resistance sensitivities when the longitudinal bias magnetic field is 25 Oe, FIG. 18B shows 40 Oe, FIG. 18C shows 55 Oe, and FIG. 18D shows 70 Oe. . As the longitudinal bias magnetic field increases, the intercept and the slope decrease.

For each of (a) to (d) in FIG. 18, the inclination a and the intercept b in the equation (44) are obtained. For c ₀ , A, and β, the coefficients are read from the measured values in FIG. Strictly speaking, the relationship between the longitudinal bias magnetic field and the differential resistance sensitivity changes as the temperature changes. However, the sensitivity of the exponential function changes when the longitudinal bias magnetic field is zero, but the degree of the change does not change. Therefore, if the characteristics of the longitudinal bias magnetic field and the differential resistance sensitivity at one temperature are measured and the coefficients of c ₀ , A, and β are obtained, they can be used practically.

FIG. 19 shows the calculation result of the magnetic field (ΔHb in equation 51) for compensating the longitudinal bias magnetic field with respect to the temperature when the longitudinal bias magnetic field is 25, 40, and 55 Oe. Referring to FIG. 19, FIG. 19A shows a case where the longitudinal bias magnetic field is 25 Oe, FIG. 19B shows a case where the longitudinal bias magnetic field is 40 Oe, and FIG. 19C shows a case where the longitudinal bias magnetic field is 55 Oe. The horizontal axis represents temperature (° C.), and the vertical axis represents magnetic field ΔHb (Oe) for compensation. The temperature compensation of the output can be performed by changing the longitudinal bias magnetic field by this ΔH in addition to the respective longitudinal bias magnetic fields.

FIG. 20 shows a graph summarizing FIGS. 19 (a) to 19 (c). The horizontal axis is the temperature (° C.), and the vertical axis is the magnetic field ΔHb (Oe) necessary for compensation. Even when temperature compensation from −40 ° C. to 140 ° C. is performed, the magnetic field adjusted for correction is about 14 Oe. Further, when the longitudinal bias magnetic field increases, the amount of change in the bias magnetic field necessary for compensation increases.

FIG. 21 shows the results of actual measurement of the differential resistance sensitivity with and without the compensation function when the sensor portion having the characteristics of FIGS. 16 and 17 is made differential and the longitudinal bias magnetic field is 40 Oe. The compensation temperature range is -7 ° C to 118 ° C. In FIG. 21A, the horizontal axis represents temperature (° C.) and the vertical axis represents differential resistance value sensitivity (Ω / Oe). In the case of no compensation (dotted line) and the case of compensation (solid line), the differential resistance sensitivity is clearly constant in the solid line. That is, the output can be stably obtained without being affected by the temperature.

FIG. 21 (b) is a graph showing changes in the longitudinal bias magnetic field for compensation obtained from the equation (51). A circle indicates a change in the longitudinal bias magnetic field actually performed at that temperature. Since the longitudinal bias magnetic field is changed at a value close to the compensation straight line obtained from the equation (51), it can be said that the temperature compensated differential resistance value sensitivity as shown in FIG.

As described above, the magnetic sensor element of the present embodiment can compensate for the temperature dependence of the output by changing the strength of the longitudinal bias magnetic field in accordance with the change in temperature. Further, the magnetic sensor element 60 of FIG. 15 can be used in place of the magnetic sensor element 10 of the power measuring device 6 shown in FIG. 3, and also has an amplifier and a current source for amplifying the output voltage. It can also be used as a magnetic sensor, a current measuring device, and a power factor measuring device.

In this embodiment, the longitudinal bias magnetic field generator 62 is composed of an electromagnet, a magnetic field sensor 64, and a controller 70. However, it may be a permanent magnet having characteristics according to the equation (51) with respect to temperature.

Since the magnetic sensor element according to the present invention can be made small and thin, it can be applied not only to the power measuring apparatus described above, but also to a power factor meter, an ammeter and a voltage system. It can be used for almost all devices that use the.

1 Circuit 2 Power supply 3 Metal A
4 Metal B
DESCRIPTION OF SYMBOLS 5 Output terminal 6 Electric power measurement apparatus 10 Magnetic sensor element 11 Sensor part 11a, 11b Electrode (measurement terminal)
12 Magnetic film 12m Magnetic film 12j Connection part 12M Magnetization 13 Lateral bias magnetic field addition means 13a Conductive film 20 Compensation metal part 20a Open ends 22a, 22b Connection terminal 24 Measuring resistor 25 Differential amplifier 26 Post-processing means 27 Detection means 30 Output terminal 32 Magnetic sensor element 33 Adjustment resistor 34 Compensation resistor 34r Resistance 34s NTC thermistor 36 Sensor unit 38 Power supply 40 Magnetic sensor element 40a Magnetic sensor terminal 40b Magnetic sensor terminal 41 First sensor unit 42 Second sensor unit 43 First bridge resistor 44 First 2 bridge resistor 45 first compensation resistor 45r resistor 45s NTC thermistor 46 second compensation resistor 46r resistor 46s NTC thermistor 47 connection point 48 connection point 50 magnetic sensor element 50a, 50b magnetic sensor terminal 51 first bridge resistor 52 second bridge resistor 60 Magnetic sensor Child 61 sensor unit 61 first sensor part 67 second sensor portion 62 a longitudinal bias magnetic field generator 63 battery 64 magnetic field sensor 65 thermometer 66 current regulator 70 controls 91 power 92 loads 93a wire

Claims (12)

A magnetic material having a magnetoresistive effect;
Compensation resistor that includes a temperature-compensating metal and a resistor connected in parallel,
A magnetic sensor element connected in series. 2. The magnetic sensor element according to claim 1, further comprising a resistor connected in series to the compensation resistor. A first compensation resistor having a portion where a resistor and a metal for temperature compensation are connected in parallel and a first sensor unit having a magnetic body having a magnetoresistive effect are connected in series,
A second compensation resistor having a portion in which a resistor and a metal for temperature compensation are connected in parallel and a second sensor unit having a magnetic body having a magnetoresistive effect are connected in series;
The terminals of the first compensation resistor and the second compensation resistor are connected to each other,
The terminals of the first sensor unit and the second sensor unit are connected to each other,
The magnetic sensor element according to claim 1, wherein the direction of the lateral bias applying means of the re-sensor part and the second sensor part is opposite. A first bridge resistor connected in series with the first compensation resistor;
The magnetic sensor according to claim 3, further comprising a second bridge resistor connected in series with the second compensation resistor. The slope and intercept when the resistance value-temperature characteristics of the first sensor unit and the second sensor unit are linearly approximated are a ₁ and b ₁ , respectively.
The slope and intercept when the differential resistance value sensitivity of the first sensor unit and the second sensor unit is linearly approximated are a ₂ and b ₂ , respectively.
The maximum compensation temperature is set to t, α is set to 1, and k ₀ is obtained by the equation (38).
2α / (1 + α) ² of 1 ≦ α ≦ 4 ranging in alpha to the slope and intercept of when approximated to a straight line when the k ₁ and k _2, respectively, in (42) represented by alpha by formula (t) The adjustment is performed so that a combined resistance of the first compensation resistor and the bridge resistor is included in a range of 10% of a temperature-dependent curve obtained by multiplying the resistance value of the first sensor unit. Or the magnetic sensor element as described in any one of Claim 4.

6. The magnetic sensor element according to claim 1, wherein the temperature compensating metal is an NTC thermistor. A magnetic body having a magnetoresistive effect, and a pair of electrodes facing each other through the magnetic body in order to pass a current through the magnetic body,
Lateral bias magnetic field applying means for generating a bias magnetic field in a direction perpendicular to the opposing direction of the electrodes;
Having electrodes at both ends, one end electrode having a temperature compensating metal connected in series to the other end of the pair of electrodes,
When the resistance value at the reference temperature between the pair of electrodes is R _B0 and the resistance value at the reference temperature between the electrodes of the temperature compensating metal is R _A0 , within 10% of the relationship of the equation (9) A temperature-compensated magnetic sensor element that is included in the range.

Here, α _A is a temperature coefficient related to the electric resistance of the temperature compensating metal, α _B is a temperature coefficient related to the electric resistance of the magnetic material, β ₀ is a value of the magnetoresistance effect at the reference temperature, and β _B is a magnetic resistance. The temperature coefficient related to the effect, t is the temperature change from the reference temperature, ΔVMR is the output voltage obtained from both ends of the magnetic material by the magnetoresistive effect, H ₀ is the externally applied magnetic field, and V ₀ is the voltage applied to the magnetic material 8. The temperature-compensated magnetic sensor element according to claim 7, wherein the lateral bias magnetic field applying means is composed of a conductor provided on the surface of the magnetic body. A magnetic sensor for detecting a magnetic field,
A temperature-compensated magnetic sensor element according to claim 1 or 2,
A current source for passing a current between both end electrodes of the temperature compensated magnetic sensor element;
A magnetic sensor comprising a voltmeter for measuring a voltage between the both end electrodes of the temperature-compensated magnetic sensor element. A power system for measuring power consumed by the load in a circuit in which a power source and a load are connected by a connection line,
The temperature-compensated magnetic sensor element according to any one of claims 7 and 8, which is disposed adjacent to the connection line,
A voltmeter for measuring the voltage across the temperature-compensated magnetic sensor element;
A sensor resistor having one end connected to one end of the temperature-compensated magnetic sensor element;
A first connection terminal provided at the other end of the temperature-compensated magnetic sensor element and a second connection provided at the other end of the sensor resistor for connecting the power supply in parallel with the load A power measuring device having a terminal. A magnetic material having a magnetoresistive effect;
A longitudinal bias magnetic field generator for applying a longitudinal bias magnetic field to the magnetic body;
When the temperature of the magnetic body rises, the strength of the longitudinal bias magnetic field decreases,
The magnetic sensor element according to claim 1, wherein the strength of the longitudinal bias magnetic field increases when the temperature of the magnetic body decreases. Constants when the relationship between the strength of the longitudinal bias magnetic field and the resistance sensitivity with respect to the magnetic material is approximated by an exponential function of Equation (47) are c ₀ , A, and β,
The slope and intercept when approximating the relationship between temperature and resistance sensitivity at the time of a specific longitudinal bias magnetic field with a straight line are a and b, respectively.
When the temperature at Δt ° C. changes from the reference temperature t, a longitudinal bias magnetic field within 10% is applied to the longitudinal bias magnetic field change (ΔHb) expressed by the equation (51). Item 12. The magnetic sensor element according to Item 11.

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