JP2547169Y2 - Current detection sensor - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a current detection sensor for detecting the direction and magnitude of a current to be detected.

[0002]

2. Description of the Related Art In recent years, a current detection sensor for detecting the magnitude and direction of a current by applying a current magnetic effect, that is, a current detection sensor using a magnetoelectric conversion element has been produced. A current detection sensor created using a Hall element, which is a type of magnetoelectric conversion element, is a typical example. An example of a current detection sensor using such a Hall element is shown in FIG.

In FIG. 5, as shown in the external view of FIG. 5A, this conventional device comprises a coil portion 11, a core 13, and an element substrate 15, and the element substrate 15 has Is provided. As shown in FIG. 5B, a Hall element 19 is provided in the Hall element section 17, and the Hall element 19 detects the Hall voltage V _H output from the Hall element 19, so that the Hall element 19 emits light from the coil 13. The intensity of the applied magnetic field is detected.

In this conventional device, an electrode for supplying a current to be detected is connected to a terminal 11a and a terminal 12a provided on the coil portion 11. In the coil portion 11, a conductive wire is wound around the core 13, and the terminal 11
The detected current flowing from 11a to 11b is
At 1, electromagnetic conversion is performed to form a magnetic field around the core 13. Then, magnetic fields generated in this manner is not a Hall voltage V _H is magnetoelectric converting the Hall element 19 of the Hall element unit 17 on the element substrate 15.

The Hall element 19 is connected to the input current terminal 1
9a and 19b, and the input current terminal 19a
And 19b are supplied with a hole current I _H from a power supply. On the other hand, the output voltage terminals 19c and 19d
When a magnetic field B is applied to the Hall element 19, a Hall voltage _VH having a magnitude following the magnitude of the magnetic field is detected between the output voltage terminals 19c to 19d. The direction of the field lines, can be detected as a code of the Hall voltage V _H, thereby the Hall element 1
9, and thus the strength and strength of the magnetic field formed around the Hall element section 17 and the magnetic pole can be analyzed.

Since the state of the magnetic field formed around the Hall element portion 17 is determined by the current to be detected supplied to the coil portion 17, the Hall voltage V _H output from the Hall element 19 is detected. Then, the magnitude and direction of the detected current supplied to the coil unit can be detected.

[0007]

However, in the conventional device formed as described above, since the coil and the core have to be set, the device becomes large and is not suitable for practical use. Limited,
It is difficult to manufacture because the setting of the coil and the installation of the core also become a design problem in the manufacturing process.
There was such a problem.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a small-sized current detection sensor having good strength accuracy without using coils and cores.

[0009]

Means for Solving the Problems In order to solve the above problems, in the current detection sensor according to the present invention,
A pair of magnetoresistive elements arranged in parallel on one magnetic pole side of the permanent magnet, and a conductor through which a current to be detected is passed, which is arranged on a plane passing between the pair of magnetoresistive elements,
A direction and a magnitude of a current to be detected flowing in the conductor are detected by detecting an electric resistance of the pair of magnetoresistive elements.

[0010]

In the current detection sensor according to the present invention having the above-described structure, a magnetic field is always applied to the pair of magnetoresistive elements from one of the pole faces of the permanent magnet in one direction.

When a current to be detected flows through the conductor, a magnetic field is generated around the conductor according to the right-hand rule. The magnetic field generated in this way disturbs the magnetic field that is always applied to the magnetoresistive element from one direction.

The disturbance of the magnetic field is generated in accordance with the magnitude and direction of the current to be detected flowing in the conductor.
By detecting the electric resistance of the magnetoresistive element determined according to the disturbance of the magnetic field, the magnitude and direction of the current to be detected flowing through the conductor can be detected.

That is, by detecting a magnetoresistive element having a changed electric resistance from among the pair of magnetoresistive elements, it is possible to detect a direction of a current to be detected flowing through the conductor. By detecting the electric resistance value of the magnetoresistive element whose electric resistance has changed, the magnitude of the current to be detected flowing through the conductor can be detected.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is an external view showing the configuration of a detection unit of a current detection sensor according to this embodiment. In this detection unit, a magnetoresistive element chip 20 is provided on a permanent magnet 19, and on this magnetoresistive element chip 20, magnetoresistive elements 21 and 22 are arranged in parallel. Are terminals 21a and 21b, and terminal 22a is
And 22b are provided respectively. And between the magnetoresistive elements 21 and 22 arranged in parallel as described above,
A conductor 23 is provided along these symmetry axes.

Here, the magnetoresistive element chip 20 is fixed on the permanent magnet 19 with an adhesive or the like, and the surface of the magnetoresistive element chip 20 is covered with an insulating coating. The magneto-resistive elements 21 and 22 on the magneto-resistive element chip 20 are formed by patterning on the magneto-resistive element chip 20 by photo etching or the like. Further, in the embodiment, the strength of the permanent magnet 19 and the resistance of the magnetoresistive elements 21 and 22 from the permanent magnet 19 are set so that the magnetic field strength received by the magnetoresistive elements 21 and 22 from the permanent magnet 19 is 0.1 T to 0.3 T. A distance up to 22 is set. Also, the permanent magnet 1
The pole face 9 is set to be equal to or larger than the magnetoresistive element chip 20. The conductor 23 provided between the magnetoresistive elements 21 and 22 is fixed with an adhesive or the like. The fixing may be performed by an insulating coating applied to the magnetoresistive element chip 20.

Next, the operation of the detection unit of the current detection sensor according to this embodiment will be described with reference to FIG. 2A shows a state before the detected current flows through the conductor 23, and FIG. 2B shows a state when the detected current flows through the conductor 23. FIG. It is operation | movement explanatory drawing.

In this embodiment, since the N pole of the permanent magnet 19 is installed toward the magnetoresistive element chip 20 side, the direction of the magnetic force lines emitted from the permanent magnet 19 is indicated by an arrow 31 in FIG. Turn upwards as you are. Here, when a current to be detected flows through the conductor 23, a magnetic field represented by a two-dot chain line 33 is formed around the conductor 23 according to the right-hand rule, as shown in FIG. Become so.

When a current to be detected flows through the conductor 23 from, for example, the near side to the far side of the page, as shown in FIG. The magnetic lines of force 31 emitted from the magnet 19 will be disturbed. At this time, the strength of the magnetic field near the magnetoresistive element 22 is weakened by the magnetic field 35 generated around the conductor 23 and the strength of the magnetic field near the magnetoresistive element 21 is increased.

Since the magnetoresistive element used in this embodiment is a compound semiconductor magnetoresistive element such as indium antimony, the electric resistance increases as the external magnetic field increases. Therefore, in the above-described example, when the detected current flows through the conductive wire 23 in the direction as in the above-described example, the electric resistance of the magnetoresistive element 22 decreases and the electric resistance of the magnetoresistive element 21 decreases. Resistance increases.

Conversely, when the electric resistance of the magneto-resistive element 21 increases and the electric resistance of the magneto-resistive element 22 decreases, as described above, the detected current increases from the near side to the far side of the page. Is flowing. However, when the electric resistance of the magnetoresistive element 22 increases and the electric resistance of the magnetoresistive element 21 decreases, the current to be detected flows in the opposite direction, that is, from the back of the paper toward the front. become. Therefore, in the present embodiment, if the detection of the magnetoresistive element having reduced electric resistance is performed,
The direction of the detected current flowing through the conductive wire 23 can be detected. In this manner, the permanent magnet 19 plays the role of a bias magnet for increasing the sensitivity of the magnetoresistive elements 21 and 22, and at the same time, plays a role of giving these magnetoresistive elements the ability to discriminate magnetic poles. That is.

The magnitude of the magnetic field 35 generated around the conductor 23 is proportional to the magnitude of the current to be detected flowing through the conductor 23, and the degree of disturbance of the magnetic field 31 emitted from the permanent magnet 19 is as follows. Magnetic field 3 generated around conductor 23
5, the magnitude of the current to be detected flowing through the conductor 23 can be detected by detecting the degree of disturbance of the magnetic field 31. Since the degree of disturbance of the magnetic field 31 emitted from the permanent magnet 19 can be detected as a change in the electric resistance of the magnetoresistive elements 21 and 22, if the electric resistance of the magnetoresistive elements 21 and 22 is detected, The magnitude of the detected current flowing can be detected. That is, the larger the change in the electric resistance of the magnetoresistive element 21 or 22, the larger the current to be detected flowing through the conducting wire 23, and conversely, the change in the electric resistance of the magnetoresistive element 21 or 22 increases. If it is small, it means that the detected current flowing through the conductor 23 is small.

FIG. 3 is a diagram showing the configuration of an embodiment of a current detection sensor having a detection section as shown in FIG.

In the current detection sensor according to the present embodiment, the detection unit shown in FIG.
Are soldered and fixed to the substrate 40 at the contact portions 42 and 44. In this case, the permanent magnet 1
9, a permanent magnet 19 and the magnetoresistive elements 21 and 22 are formed in the substrate 40 by making holes for filling the permanent magnet.
Therefore, it is possible to adjust the magnetic field strength received by the magnetoresistive elements 21 and 22 from the permanent magnet 19 to be 0.1T to 0.3T, for example.

FIG. 4 is a block diagram showing a functional configuration of a circuit when current detection is performed using the current detection sensor as shown in FIG.

As shown in FIG. 4, the current detection sensor in this embodiment is connected to a constant voltage source 46, and furthermore, a voltmeter 48 is installed to
The potential difference before and after is detected. Therefore, a voltage change proportional to the magnitude of the detected current I flowing through the conductive wire 23 can be read by the voltmeter 48, and the direction of the detected current I can be detected in the ± direction of the voltmeter 48. .

In this embodiment, the terminals 21a and 21b are provided before and after the magnetoresistive element 21, and the terminals 22a and 22b are provided before and after the magnetoresistive element 22, respectively. This can be performed before and after the resistance element 22, and can also be performed before and after the magnetoresistance element 21. In addition, it is also possible to perform processing by taking the difference between the voltage before and after the magnetoresistive element 21 and the voltage before and after the magnetoresistive element 22, and this can be freely selected in the equipment in which the present apparatus is set. Is preferred. In any case, since it has four output terminals, many application examples can be set.

In this example, indium antimony was used as the compound semiconductor magnetoresistive element.
The compound semiconductor used is not limited to this, but any compound semiconductor magnetoresistive element such as nickel antimony, indium arsenide, gallium arsenide and the like can be used.

[0029]

As described above, the current detection sensor according to the present invention has a simple configuration in which a magnetoresistive element is arranged on a permanent magnet and a conductor for flowing a current to be detected is placed on the magnetoresistive element. Therefore, there is an advantage that it can be manufactured small, light, and inexpensively.

In addition, since the resistance change of the magnetoresistive elements arranged in parallel on the permanent magnet changes differentially with each other due to the bias magnetic field by the permanent magnet, high-sensitivity detection can be performed.

Further, since the conductor through which the current to be detected flows can be set on the same chip as the chip on which the magnetoresistive element is installed, the sensor can be more easily assembled, and a smaller, lighter and cheaper sensor can be provided. Can be provided. At the same time, the conductor through which the current to be detected flows and the magnetoresistive element for detection can be set extremely close to each other, so that a highly sensitive current detection sensor can be provided.

[Brief description of the drawings]

FIG. 1 is an external view illustrating a configuration of a detection unit of a current detection sensor according to an embodiment of the present invention.

FIG. 2 is an operation explanatory diagram illustrating an operation of a detection unit in FIG. 1;

FIG. 3 is a diagram showing a configuration of a current detection sensor provided with the detection unit of FIG. 1;

FIG. 4 is a block diagram illustrating a circuit configuration of the current detection sensor according to the embodiment.

FIG. 5 is a diagram showing a configuration of a conventional current detection sensor, that is, a current detection sensor using a Hall element.

[Explanation of symbols]

 Reference Signs List 19 permanent magnet 20 magnetoresistive element chip 21, 22 magnetoresistive element 23 conductor (conductor)

Claims (1)

(57) [Scope of request for utility model registration] 1. A pair of magnetoresistive elements arranged in parallel on one magnetic pole side of a permanent magnet, a conductor through which a current to be detected is arranged, disposed on a plane passing between the pair of magnetoresistive elements, A current detection sensor comprising: detecting a direction and a magnitude of a current to be detected flowing through the conductor by detecting an electric resistance of the pair of magnetoresistive elements.