JP2011196698A - Current detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a current detector reduced in current consumption and small n size, and excellent in the linearity of an output.SOLUTION: The current detector is so constituted that the normal line direction of an insulating substrate in a magnetoresistive element sensor 25 is inclined in the direction of a magnetic field generated by a current flowing through a conductor 23. Thereby a component of the magnetic field generated by the current flowing through the conductor 23 which acts on a magnetoresistive element is reduced equivalently and the current flowing through the conductor 23 is measured with excellent linearity and low current consumption.

Description

  The present invention relates to a current detection device that detects a large current in vehicles, industrial equipment, and the like.

  As conventional current detection devices, those shown in FIGS. 7 to 9 are known (see Patent Document 1). FIG. 7A shows an external perspective view of a conventional current detection device. The current detection device passes a conductor 3 through a tunnel portion 2 of a resin-made case 1, and then the vehicle is moved by the flange 4 together with the case 1. It is attached and fixed to a body or the like (not shown). FIG. 7B is a cross-sectional view taken along the line AA in FIG. 7A, and is formed by resin molding so that the compensation current line 5, the magnetoresistive element portion 6, and the permanent magnet 7 maintain a predetermined positional relationship. It is fixed by the formed holder 8. Reference numeral 9 denotes a magnetic yoke for converging the magnetic flux generated from the current flowing through the conductor 3, and is made of a magnetic material or the like. Reference numeral 10 denotes a circuit board on which circuit components constituting the circuit are mounted.

  FIG. 8A shows the structure of the magnetoresistive element portion and the direction of the applied magnetic field. In the magnetoresistive element section 6 shown in FIG. 8A, the magnetoresistive elements 6a, 6b, 6c, and 6d, each of which has a magnetic directivity by bending a plurality of magnetoresistive thin films back on the insulating substrate 11, are shown in the figure. Are arranged so that the directions of current flow are orthogonal to each other, connected to form a bridge configuration, and lead-out electrodes A, B, C, and D are provided to the outside. A vector α indicates a bias magnetic field generated by the permanent magnet 7 and determines an operating point in the magneto-resistance characteristics of the magnetoresistive elements 6a, 6b, 6c, and 6d. The vectors β and γ indicate the magnetic fields applied to the magnetoresistive elements 6a, 6b, 6c and 6d by the current flowing through the conductor 3 and the compensation current line 5, respectively. FIG. 8B shows an electrical equivalent circuit diagram of the magnetoresistive element section 6.

  FIG. 9 is a circuit diagram for explaining the operation of the conventional current detecting device. A power supply 12 for applying a constant voltage is connected between a coupling point A of the magnetoresistive elements 6a and 6b and a coupling point D of the magnetoresistive elements 6c and 6d in the magnetoresistive element section 6. Reference numeral 13 denotes a detection unit that detects a potential difference between the coupling point C of the magnetoresistive elements 6a and 6d and the coupling point B of the magnetoresistive elements 6b and 6c. The current control unit 14 uses the output signal of the detection unit 13 to make the compensation current line 5 The current that flows in the is controlled. Reference numeral 15 denotes an output converter, which amplifies a voltage drop at the load resistor 16 due to a current flowing through the compensation current line 5 and outputs the amplified voltage drop to the output terminal 17.

  When the current flowing through the conductor 3 is zero, only the bias magnetic field α shown in FIG. 8A is applied so as to form a certain angle (45 degrees) with respect to the magnetoresistive elements 6a, 6b, 6c and 6d. The magnetoresistive elements 6a, 6b, 6c and 6d have substantially the same resistance value. For this reason, the magnetoresistive element bridge is balanced, and the coupling point C of the magnetoresistive elements 6 a and 6 d and the coupling point B of the magnetoresistive elements 6 b and 6 c have the same potential, and no signal is output from the detection unit 13. As a result, no current flows through the compensation current line 5 and the load resistor 16, so that no output voltage appears at the output terminal 17.

  On the other hand, when a current flows through the conductor 3, the magnetic field β shown in FIG. 8A is generated and applied to the magnetoresistive elements 6a, 6b, 6c, and 6d. Therefore, the resistance of the magnetoresistive elements 6a and 6c is large. At the same time, the resistances of the magnetoresistive elements 6b and 6d are reduced. For this reason, the balance of the magnetoresistive element bridge is broken, and a potential difference is generated between the coupling point C of the magnetoresistive elements 6a and 6d and the coupling point B of the magnetoresistive elements 6b and 6c. This potential difference is detected by the detection unit 13 and input to the current control unit 14. Then, the current control unit 14 causes a current to flow through the compensation current line 5 based on this potential difference, generates the magnetic field γ shown in FIG. 8A, cancels out the magnetic field β received from the conductor 3, and magnetoresistive element The net magnetic field applied to 6a, 6b, 6c, and 6d is only the magnetic field α generated by the permanent magnet 7, thereby operating the magnetoresistive element bridge to have a potential difference of zero. When the magnetoresistive element bridge is balanced again in this way, a signal corresponding to the current flowing through the conductor 3 is output to the output terminal 17 if the voltage generated at both ends of the load resistor 16 is monitored and amplified appropriately. become.

  In general, magnetoresistive elements are characterized by high magnetic sensitivity, but changes in magnetoresistance with respect to changes in the magnetic field applied to the magnetoresistive elements are non-linear, and characteristic deterioration occurs with temperature, time, etc. There was a problem that there was. On the other hand, in the conventional current detection device, the magnetic field applied to the magnetoresistive elements 6a, 6b, 6c and 6d is substantially generated by the permanent magnet 7 even when a current is flowing through the conductor 3. Therefore, the non-linear magneto-resistance characteristic of the magnetoresistive element and the characteristic deterioration due to temperature, time, etc. are not involved in the characteristic as the current detection device at all, and the current flowing through the conductor 3 And the linearity between the output signals of the current detectors are kept good.

  As prior art document information relating to the invention of this application, for example, Patent Document 1 is known.

Japanese Unexamined Patent Publication No. 7-92199

  However, in the conventional current detection apparatus shown in FIGS. 7 to 9, when a large current flows through the conductor 3, the current to be passed through the compensation current line 5 increases accordingly, so that the current consumption of the sensor increases. There was a problem that it was. This problem will be described with reference to FIG. In general, the strength H of the magnetic field generated around the current line is proportional to the current flowing through the current line and inversely proportional to the distance from the current line. Therefore, in FIG. 7B, the effective distance between the conductor 3 through which a current of 10 A flows and the magnetoresistive element unit 6 is 20 mm, and the distance between the compensation current line 5 and the magnetoresistive element unit 6 is If it is 1 mm, a large current of 0.5 A must flow through the compensation current line 5. If the effective distance between the conductor 3 and the magnetoresistive element portion 6 is increased, the current flowing through the compensation current line 5 can be reduced. In this case, however, the shape of the sensor itself is increased. .

  SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and an object of the present invention is to provide a current detection device that consumes less current, is small, and has excellent output linearity.

  In order to achieve the above object, the present invention has the following configuration.

  According to a first aspect of the present invention, there is provided a current detecting device for detecting a current flowing through a conductor, wherein an insulating substrate and a magnetic detection direction of an adjacent magnetoresistive element disposed on the insulating substrate are set. Four magnetoresistive elements coupled in a bridge shape orthogonal to each other, and disposed on the insulating substrate in the vicinity of the magnetoresistive element, and approximately 45 with respect to the magnetic detection direction of the magnetoresistive element. A magnetoresistive element sensor comprising a magnetic field generating means for applying a bias magnetic field in a direction in which the magnetoresistive element is disposed; a compensation current line disposed on the insulating substrate in the vicinity of the magnetoresistive element; A power source that applies a constant voltage between the two coupling portions, a detection means that detects a potential difference between opposing coupling portions other than between the coupling portions to which a constant voltage is applied by the power source, and Based on output signal Current control means for controlling the current flowing through the compensation current line so as to make the potential difference zero, and a circuit unit for converting and outputting the current flowing through the compensation current line, and the bias magnetic field direction and the conductor The direction of the flowing current is parallel, and the normal direction of the insulating substrate is inclined with respect to the direction of the magnetic field generated by the current flowing through the conductor. According to this configuration, the direction of current flowing through the conductor is generated. Since the magnetic field is applied with an inclination to the magnetoresistive element, the component acting on the magnetoresistive element of the magnetic field generated by the current flowing through the conductor can be reduced equivalently, thereby reducing the shape of the detection device. The effect is that the current to be measured can be measured with good linearity and low current consumption without increasing it.

  According to a second aspect of the present invention, there is provided a current detecting device for detecting a current flowing through a conductor, wherein an insulating substrate and a magnetic detection direction of an adjacent magnetoresistive element disposed on the insulating substrate are set. Four magnetoresistive elements coupled in a bridge shape orthogonal to each other, and disposed on the insulating substrate in the vicinity of the magnetoresistive element, and approximately 45 with respect to the magnetic detection direction of the magnetoresistive element. Two or more magnetoresistive element sensors comprising magnetic field generating means for applying a bias magnetic field in a direction in which the magnetic field is generated; and a compensation current line disposed on the insulating substrate in the vicinity of the magnetoresistive element; A power supply that applies a constant voltage only between two opposing coupling portions of the magnetoresistive element in any one of the magnetoresistive element sensors selected from the above magnetoresistive element sensors, and the selected magnetoresistive element sensor In Detecting means for detecting a potential difference between opposite coupling portions other than between the coupling portions to which a constant voltage is applied by the power source, and based on an output signal from the detection means in the selected magnetoresistive element sensor Current control means for controlling the current flowing through the compensation current line so that the potential difference becomes zero, and one of the magnetoresistive element sensors has the bias magnetic field direction parallel to the direction of the current flowing through the conductor. And the normal direction of the insulating substrate in the magnetoresistive element sensor is orthogonal to the direction of the magnetic field generated by the current flowing in the conductor, and the other magnetoresistive element sensors have a magnetic field generated by the current flowing in the conductor. The normal direction of the insulating substrate in the magnetoresistive element sensor is inclined with respect to the direction. According to this configuration, the current flowing in the conductor is Is selected, the magnetoresistive element sensor arranged so that the normal direction of the insulating substrate of the magnetoresistive element and the magnetic field generated by the current flowing through the conductor are orthogonal to each other, while the current flowing through the conductor is large By selecting a magnetoresistive element sensor arranged so that the normal direction of the insulating substrate of the magnetoresistive element and the magnetic field generated by the current flowing through the conductor are inclined, a wide range without increasing the shape of the detection device The current to be measured can be measured with good linearity and low current consumption.

  The invention described in claim 3 of the present invention particularly uses a thin film magnet as the magnetic field generating means. According to this configuration, the thin film magnet is formed on the magnetoresistive element by means such as sputtering, and By patterning using photolithography technology, the magnetic field generating means and the magnetoresistive element can be integrally and extremely close to each other, and can be arranged with high precision, so that the current to be measured can be further accurately It has the effect that it can be measured.

  The invention described in claim 4 of the present invention uses a winding coil as the compensation current line. According to this configuration, the magnetic field generated by the current flowing through the compensation current line is multiplied by the number of turns of the winding. Since the current flowing through the compensation current line can be further reduced, the current to be measured can be measured with good linearity and low current consumption.

  As described above, the physical quantity sensor of the present invention is a current detection device that detects a current flowing through a conductor, and the magnetic detection directions of the insulating substrate and the adjacent magnetoresistive elements disposed on the insulating substrate are mutually Four magnetoresistive elements coupled in a bridge shape in an orthogonal state, and disposed on the insulating substrate in the vicinity of the magnetoresistive element, and approximately 45 degrees with respect to the magnetic detection direction of the magnetoresistive element. A magnetoresistive element sensor comprising a magnetic field generating means for applying a bias magnetic field in the direction of forming a magnetic field, a compensation current line disposed on the insulating substrate in the vicinity of the magnetoresistive element, and the magnetoresistive element facing each other. A power source for applying a constant voltage between two coupling portions; a detecting means for detecting a potential difference between opposing coupling portions other than between the coupling portions to which a constant voltage is applied by the power source; and an output from the detecting means Based on signal Current control means for controlling the current flowing through the compensation current line so as to make the potential difference zero, and a circuit unit for converting and outputting the current flowing through the compensation current line, the bias magnetic field direction and the conductor The direction of the current flowing through the conductor is parallel, and the normal direction of the insulating substrate is inclined with respect to the direction of the magnetic field generated by the current flowing through the conductor. Applied to the magnetic field, the component acting on the magnetoresistive element of the magnetic field generated by the current flowing in the conductor can be equivalently reduced, and without increasing the shape of the detection device, This provides an excellent effect that the current to be measured can be measured with good linearity and low current consumption.

(A) Perspective view of current detection device according to embodiment 1 of the present invention, (b) Cross-sectional view along line BB in (a) (A) Top view of magnetoresistive element sensor in the same current detection device, (b) CC sectional view in (a) Enlarged sectional view of the vicinity of the magnetoresistive element sensor in the same current detection device Circuit diagram for explaining the operation of the current detection device (A) Perspective view of current detection device according to embodiment 2 of the present invention, (b) A sectional view taken along the line DD in (a), and an enlarged view of portion A in (c) and (b) (A) The perspective view which shows the magnetoresistive element sensor of the electric current detection apparatus in Embodiment 3 of this invention, (b) The EE sectional view taken on the line in (a) (A) Perspective view of conventional current detection device, (b) AA line sectional view in (a) (A) The figure which shows the structure of the magnetoresistive element part in the same electric current detection apparatus, and the direction of the applied magnetic field, (b) The electrical equivalent circuit schematic of the magnetoresistive element part Circuit diagram for explaining the operation of the current detection device

(Embodiment 1)
Hereinafter, the first and third aspects of the present invention will be described with reference to the first embodiment. FIG. 1A shows a perspective view of a current detection device according to Embodiment 1 of the present invention. This current detection device passes a conductor 23 through a tunnel portion 22 of a resin case 21, and then the case 21 Each flange 24 is attached and fixed to the body of a vehicle (not shown). FIG. 1B is a sectional view taken along line BB in FIG. 1A, and a magnetoresistive element sensor 25 is fixed on a pedestal 26 formed by resin molding. Reference numeral 27 denotes a magnetic yoke for converging the magnetic flux generated from the current to be measured. The magnetic yoke 27 is made of a magnetic thin film and the like, and the magnetoresistive element sensor 25 is placed in a gap 28 formed in the magnetic yoke 27. Is arranged. Reference numeral 29 denotes a circuit board on which circuit components (not shown) are mounted. When a current to be measured flows through the conductor 23, a magnetic field is generated around the conductor 23. This magnetic field is confined in the magnetic yoke 27 and radiated uniformly in the gap 28. The magnetoresistive element sensor 25 is arranged so that the normal direction of the insulating substrate is inclined with respect to the magnetic field formed in the gap 28 in this way.

  2A is a top view of the magnetoresistive element sensor 25, and FIG. 2B is a cross-sectional view taken along line CC in FIG. 2A. 2A and 2B, 30a, 30b, 30c, and 30d are magnetoresistive elements formed on an insulating substrate 31 such as ceramic, and these have a thickness of about 0 made of a ferromagnetic material such as Ni-Co. .1 μm magnetoresistive thin film. The magnetoresistive elements 30a and 30b and the magnetoresistive elements 30c and 30d are connected in series, and the longitudinal directions of the patterns, which are the magnetic detection directions, are orthogonal to each other. The input electrode 32a is formed on the insulating substrate 31, and is electrically connected to the magnetoresistive element 30a and the magnetoresistive element 30d. The first output electrode 32b is also formed on the insulating substrate 31, and is electrically connected to the magnetoresistive element 30a and the magnetoresistive element 30b. Similarly, the ground electrode 32c and the second output electrode 32d are also formed on the insulating substrate 31, and are electrically connected to the magnetoresistive element 30b and the magnetoresistive element 30c, and the magnetoresistive element 30c and the magnetoresistive element 30d, respectively. It is connected.

Reference numeral 33a denotes a first insulating layer, and the first insulating layer 33a is made of a SiO ₂ thin film having a thickness of about 1 μm, and is made of a thin film magnet 34 described later by covering the magnetoresistive elements 30a, 30b, 30c, 30d. It electrically insulates from the bias magnetic field generating means.

  Reference numeral 34 denotes a thin film magnet. The thin film magnet 34 is made of CoPt or the like having a thickness of about 0.6 μm. The thin film magnet 34 is formed on the first insulating layer 33a by vapor deposition or sputtering, and then patterned by exposure and etching. Thus, the magnetic resistance elements 30a, 30b, 30c, and 30d are divided into a plurality of substantially rectangular parallelepipeds having a longitudinal direction in a direction that forms 45 degrees with the magnetic detection direction. Then, by applying an extremely large magnetic field in the width direction of the plurality of substantially rectangular thin films, the thin film having a substantially rectangular shape is magnetized in the width direction, and the thin film magnet 34 can be obtained. When the XYZ axes are defined as shown in FIG. 2A, a magnetic field in the Y-axis direction is generated from the thin film magnet 34, and 45 degrees with respect to the magnetic detection direction of the magnetoresistive elements 30a, 30b, 30c, 30d. A bias magnetic field is applied in the direction formed.

Reference numeral 33b denotes a second insulating layer, and the second insulating layer 33b is made of a SiO ₂ thin film having a thickness of about 1 μm, and electrically insulates from a compensation current line 35 described later by covering the thin film magnet 34. It is.

  Reference numeral 35 denotes a compensation current line. This compensation current line 35 is made of a copper thin film having a thickness of about 0.6 μm, and is formed on the second insulating layer 33b by vapor deposition or the like, and then patterned by exposure and etching. It is formed by.

  With the above-described configuration, the magnetoresistive elements 30a, 30b, 30c, and 30d, the thin film magnet 34, and the compensation current line 35 are integrally and extremely close to each other on the insulating substrate 31 with high accuracy. It is something that can be done.

Figure 3 is an illustration on an enlarged scale the vicinity of the magnetoresistive element sensor 25 of FIG. 1 (b), the magnetic field in FIG. 3, H _I is generated in the gap 28 of the magnetic yoke 27 by the current flowing in the conductor 23 are shown, the magnetoresistive element sensor 25 is a normal direction of the insulating substrate is inclined by an angle θ in the magnetoresistive element sensor relative to the magnetic field H _I. When the XYZ axes are defined for the magnetoresistive element sensor 25 in the same manner as in FIG. 2A, the bias magnetic field H _B generated from the thin film magnet 34 is applied in the Y axis direction. H _c is a magnetic field generated by the current flowing through the compensation current line 35 and is in the X-axis direction.

  FIG. 4 is a circuit diagram for explaining the operation of the current detecting device according to the first embodiment of the present invention. As shown in FIG. 4, the input electrode 32a and the ground electrode of the magnetoresistive element sensor 25 are shown. A power source 36 for applying a constant voltage is connected between the power source 32c and the terminal 32c. In FIG. 4, reference numeral 37 denotes a detection unit that detects a potential difference between the first output electrode 32 b and the second output electrode 32 d, and the current control unit 38 flows to the compensation current line 35 by the output signal of the detection unit 37. The current is controlled. Reference numeral 39 denotes an output conversion unit, which amplifies a voltage drop at the load resistor 40 due to a current flowing through the compensation current line 35 and outputs the amplified voltage drop to the output terminal 41.

When the current flowing through the conductor 23 is zero, only the bias magnetic field H _B shown in FIG. 3 is applied at a certain angle (45 degrees) with respect to the magnetoresistive elements 30a, 30b, 30c, and 30d. The magnetoresistive elements 30a, 30b, 30c, and 30d have substantially the same resistance value. For this reason, the magnetoresistive element bridge is balanced, the first output electrode 32 b and the second output electrode 32 d have the same potential, and no signal is output from the detection unit 37. As a result, no current flows through the compensation current line 35 and the load resistor 40, so that no output voltage appears at the output terminal 41.

When a current flows through the conductor 23, is applied to the magnetoresistive element sensor 25 a magnetic field H _I shown is generated in FIG. 3, the magneto-resistive element 30a, with 30c of resistance decreases, the magnetoresistive element 30b, 30d of the resistor Becomes larger. For this reason, the balance of the magnetoresistive element bridge is broken, and a potential difference is generated between the first output electrode 32b and the second output electrode 32d. This potential difference is detected by the detection unit 37 and input to the current control unit 38. Based on this potential difference, the current control unit 38 causes a current to flow through the compensation current line 35 to generate the magnetic field H _c shown in FIG. 3, and the net magnetic field applied to the magnetoresistive elements 30a, 30b, 30c, and 30d. By using only the bias magnetic field H _B generated from the thin film magnet 34, the magnetoresistive element bridge operates to make the potential difference zero. Thus, when the magnetoresistive element bridge is balanced again, if the voltage generated at both ends of the load resistor 40 is monitored and amplified appropriately, a signal corresponding to the current flowing through the conductor 23 is output to the output terminal 41. .

Thus, in the current detection device according to the first embodiment of the present invention, the magnetic field applied to the magnetoresistive elements 30a, 30b, 30c, and 30d is substantially equal even when a current is flowing through the conductor 23. Since only the constant magnetic field H _B generated from the thin-film magnet 34 is present, the nonlinear magneto-resistance characteristics of the magnetoresistive element and the characteristics degradation due to temperature, time, etc. are not involved in the characteristics of the current detection device at all. The linearity between the current flowing through the conductor 23 and the output signal of the current detection device is kept good.

In this case, since the above as described above magnetoresistive element sensor 25 is inclined in the normal direction of the insulating substrate in the magnetoresistive element sensor relative to the magnetic field H _I by an angle theta, magnetoresistive elements 30a, 30b, 30c , 30d, the strength of the magnetic field applied in the magnetic detection direction is H _I cos θ, which is smaller than H _I. For this reason, the current to be passed through the compensation current line 35 in order to cancel out this magnetic field strength H _I cos θ is small. Thus, the current to be measured can be measured with good linearity and low current consumption without increasing the shape of the detection device.

(Embodiment 2)
The second aspect of the present invention will be described below with reference to the second embodiment. 5A is a perspective view of the current detection device according to Embodiment 2 of the present invention, FIG. 5B is a cross-sectional view taken along the line DD in FIG. 5A, and FIG. 5C is FIG. FIG. In the second embodiment of the present invention, components having the same configuration as the configuration of the first embodiment of the present invention described above are denoted by the same reference numerals, and the description thereof is omitted.

5A, 5B, and 5C, the second embodiment of the present invention is different from the first embodiment of the present invention described above in the gap 28 formed in the magnetic yoke 27. FIG. 2 are arranged on a base 47 formed by resin molding, and the magnetoresistive element sensor 45 is placed in the gap 28 by a current flowing through the conductor 23. The normal direction of the insulating substrate in the magnetoresistive element sensor 45 is inclined by an angle θ with respect to the generated magnetic field H _I , and the magnetoresistive element sensor 46 is in contact with the magnetic field H _I. The normal line direction of the insulating substrate in FIG. Bias magnetic fields H _B1 and H _B2 generated from a thin film magnet formed on an insulating substrate in the magnetoresistive element sensors 45 and 46 are applied in a direction perpendicular to the paper surface. H _C1 and H _C2 are magnetic fields generated by a current flowing through a compensation current line formed on the insulating substrate in each of the magnetoresistive element sensors 45 and 46, and are applied in a direction along the surface of each insulating substrate. .

When the current flowing through the conductor 23 is small, a constant voltage is applied only between the input electrode of the magnetoresistive element sensor 46 and the ground electrode, and the output of the detection unit 37b is connected to the current control unit 38. The current control unit 38 controls the current flowing through the compensation current line 35 so that the net magnetic field applied to the magnetoresistive element sensor 46 is only the bias magnetic field H _B2 . If the voltage generated at both ends of the load resistor 40 is monitored and amplified appropriately by this current, a signal corresponding to the current flowing through the conductor 23 is output to the output terminal 41. When the current flowing through the current to be measured increases, a constant voltage is applied only between the input electrode of the magnetoresistive element sensor 45 and the ground electrode, and the output of the detection unit 37a is connected to the current control unit 38. The current control unit 38 controls the current flowing through the compensation current line 35 so that the net magnetic field applied to the magnetoresistive element sensor 45 is only the bias magnetic field H _B1 . If the voltage generated at both ends of the load resistor 40 is monitored and amplified appropriately by this current, a signal corresponding to the current flowing through the conductor 23 is output to the output terminal 41. With such a configuration, it is possible to obtain an effect that a wide range of currents to be measured can be measured with high linearity and low current consumption without increasing the shape of the detection device.

  Although the object of the present invention can be achieved even if the magnetic yoke 27 used in the first and second embodiments of the present invention is deleted, it is generated from the conductor 23 when the magnetic yoke 27 is not used. It is desirable to provide a magnetic shield that covers the case 21 so that the magnetic field does not leak outside.

(Embodiment 3)
The third embodiment of the present invention will be described below in particular. FIG. 6A is a perspective view showing a magnetoresistive element sensor of the current detection device according to Embodiment 3 of the present invention, and FIG. 6B is a cross-sectional view taken along line EE in FIG.

  6A and 6B, the magnetoresistive element sensor of the current detecting device according to the third embodiment of the present invention is the magnetoresistive element sensor of the current detecting device according to the first and second embodiments of the present invention shown in FIG. The difference is that the winding coil 50 is wound around the insulating substrate 31 to form a compensation current line. By adopting such a configuration, the magnetic field generated by the current flowing through the compensation current line can be increased by the number of turns of the winding, so that the current flowing through the compensation current line can be further reduced. The effect is obtained that the current can be measured with good linearity and with low current consumption.

  The current detection device of the present invention can equivalently reduce the component acting on the magnetoresistive element of the magnetic field generated by the current flowing through the conductor, thereby reducing the current to be measured without increasing the shape of the detection device. It has the effect of being able to measure with low current consumption with good linearity, and is particularly useful as a current detection device for detecting current in vehicles, industrial equipment and the like.

23 conductor 25 magnetoresistive element sensor 30a, 30b, 30c, 30d magnetoresistive element 31 insulating substrate 34 thin film magnet 35 compensating current line 36 power supply 45, 46 magnetoresistive element sensor 50 winding coil

Claims (4)

4 is a current detection device for detecting a current flowing in a conductor, and is connected in a bridge shape in a state where an insulating substrate and magnetic detection directions of adjacent magnetoresistive elements disposed on the insulating substrate are orthogonal to each other. A plurality of magnetoresistive elements, and a magnetic field generating means that is disposed on the insulating substrate in the vicinity of the magnetoresistive elements and applies a bias magnetic field in a direction that forms approximately 45 degrees with respect to the magnetic detection direction of the magnetoresistive elements A constant voltage is applied between the magnetoresistive element sensor comprising a compensation current line disposed on the insulating substrate in proximity to the magnetoresistive element, and two coupling portions of the magnetoresistive element facing each other. Detecting a potential difference between a power source, a coupling portion facing each other other than a coupling portion to which a constant voltage is applied by the power source, and setting the potential difference to zero based on an output signal from the detection unit To the above A current control means for controlling the current flowing through the compensation current line, and a circuit unit for converting and outputting the current flowing through the compensation current line, wherein the bias magnetic field direction and the direction of the current flowing through the conductor are parallel, And a current detection device in which a normal direction of the insulating substrate is inclined with respect to a direction of a magnetic field generated by a current flowing through the conductor. 4 is a current detection device for detecting a current flowing in a conductor, and is connected in a bridge shape in a state where an insulating substrate and magnetic detection directions of adjacent magnetoresistive elements disposed on the insulating substrate are orthogonal to each other. A plurality of magnetoresistive elements, and a magnetic field generating means that is disposed on the insulating substrate in the vicinity of the magnetoresistive elements and applies a bias magnetic field in a direction that forms approximately 45 degrees with respect to the magnetic detection direction of the magnetoresistive elements And two or more magnetoresistive element sensors comprising compensation current lines disposed on the insulating substrate in proximity to the magnetoresistive element, and the two or more magnetoresistive element sensors. A power source that applies a constant voltage only between two opposing coupling portions of the magnetoresistive element in any one of the magnetoresistive element sensors, and a constant voltage that is applied by the power source in the selected magnetoresistive element sensor Detecting means for detecting a potential difference between opposing coupling parts other than between the coupled parts, and setting the potential difference to zero based on an output signal from the detecting means in the selected magnetoresistive element sensor. Current control means for controlling a current flowing through the compensation current line, wherein one of the magnetoresistive element sensors is configured such that the direction of the bias magnetic field is parallel to the direction of the current flowing through the conductor, and the current flowing through the conductor The normal direction of the insulating substrate in the magnetoresistive element sensor is orthogonal to the direction of the magnetic field generated by the other magnetoresistive element sensor. A current detection device in which the normal direction of the insulating substrate in the sensor is inclined. 3. A current detecting device according to claim 1, wherein a thin film magnet is used as the magnetic field generating means. The current detection device according to claim 1, wherein a winding coil is used as the compensation current line.

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