JP2000039472A - Magnetic sensor and method for regulating characteristics of magnetic sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce unevenness of a resistance value or sensitivity of a magnetic sensor, by adding a magnetic element for regulating a bias magnetic field to a magnet provided at a lower part of a magnetoresistance element to apply the field. SOLUTION: A magnetic element 2 is provided at a lower part of a magnet 1 to regulate a resistance value or sensitivity of a magnetic sensor, by changing an intensity of a bias magnetic field to be applied to a magnetoresistance element 3. As the element 2, an iron plate is used, its cost is low, and there is a merit of finely regulating the intensity of the field. Further, a cobalt, a nickel or the like may be used. A shape of the element is arbitrary. The element may be provided not to be limited to upper and lower parts of the magnet but to be at a side face.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic sensor and the like, and more particularly, to a magnetic resistance element used as a rotation sensor, an angle sensor, a magnetic identification sensor, a steel ball sensor, a proximity sensor, and the like. The present invention relates to a magnetic sensor and the like used.

[0002]

2. Description of the Related Art Conventionally, magnetic sensors using a magnetoresistive element have been widely used for detecting magnetism. The magnetoresistive element is an element whose resistance value changes according to a change in magnetic flux density, and is formed from a semiconductor such as InSb.

FIG. 7 is a sectional view showing a conventional magnetic sensor. The magnetic sensor includes a magnetoresistive element 21 and a magnet 22 provided below the magnetoresistive element 21 for applying a bias magnetic field to the magnetoresistive element 21.
And These magnetoresistive element 21 and magnet 2
2 is fixed in the housing 25 to form a magnetic sensor.

The magnetoresistive element 21 includes a pattern surface 23 serving as a magnetic sensing portion and a base portion 24 for forming the pattern surface 23.
It is composed of The pattern surface 23 is, for example, In
It is made of a material such as Sb, and a material obtained by polishing single crystal InSb or a material formed by vapor deposition is used.

The magnetoresistive element 21 detects a change in a magnetic field applied to a pattern surface 23 serving as a magnetic sensing portion. That is, when the magnetic body approaches above the pattern surface 23 of the magnetoresistive element 21, the magnetic field applied to the pattern surface 23 changes accordingly. The magnetoresistive element 21 outputs a change in the magnetic field as a signal.

In this conventional example, a magnet 22 for applying a bias magnetic field to the magnetoresistive element 21 is provided below the magnetoresistive element 21. Usually, the output signal voltage of the magnetoresistive element is very weak, so that it is difficult to handle it as it is. Therefore, in this conventional example, the magnet 2
2, a bias magnetic field is applied to the magnetoresistive element 21 to move the magnetic operating point, and the output signal level can be increased with respect to a minute change in the magnetic field.

[0007]

However, the conventional magnetic sensor has the following problems. That is,
The conventional magnetic sensor has a problem that when the resistance value of the magnetoresistive element and the magnetic flux density of the magnet vary, there is no means for adjusting them, so that the resistance value and the sensitivity of the magnetic sensor vary. Was. In addition, when the magnetic sensor greatly varies in resistance value and sensitivity and deviates from the standard, the magnetic sensor has to be discarded as a defective product.

Accordingly, it is an object of the present invention to provide a magnetic sensor whose characteristics can be adjusted by simple means when the resistance value and the sensitivity of the magnetic sensor vary.

[0009]

SUMMARY OF THE INVENTION The present invention is directed to a magnetic sensor using a magnetoresistive element, and has the following structure in order to solve the above-mentioned technical problem. I have.

That is, the present invention provides a magnetoresistive element,
A magnet provided below the magnetoresistive element for applying a bias magnetic field to the magnetoresistive element; and a magnetic body provided in addition to the magnet for adjusting the intensity of the bias magnetic field. Is a magnetic sensor.

As described above, by providing a magnetic body in addition to the magnet, the intensity of the bias magnetic field applied to the magnetoresistive element can be adjusted. Therefore,
Since the resistance value and sensitivity of the magnetic sensor can be fine-tuned,
Variations in the resistance value and sensitivity of the magnetic sensor can be reduced. In addition, the characteristics of the magnetic sensor that has been discarded because the resistance value and the sensitivity are out of the standard can be adjusted, and the yield can be improved.

[0012]

1 to 6 show an embodiment of the present invention.
This will be described with reference to FIG.

FIG. 1 shows a magnetic sensor in which a magnetic body 2 is provided below a magnet 1. Thus, by providing the magnetic body 2 below the magnet 1, the intensity of the bias magnetic field applied to the magnetoresistive element 3 can be changed, and the resistance value and sensitivity of the magnetic sensor can be adjusted.

For example, in the embodiment shown in FIG.
In a magnetic sensor having a 5 mm × 5 mm × 6 mm ferrite magnet as the magnet 1 and a 1 mm thick iron plate as the magnetic body 2, the input resistance is 1 kΩ when the iron plate is not provided below the ferrite magnet. As a result, it increased to 1.03 kΩ. Further, in the same magnetic sensor, 1.5 times above the magnetoresistive element 3.
When the detection object is brought closer to the distance of 0.2 mm, the detection power is 40 mm lower than when the iron plate is not provided below the ferrite magnet.
It increased by 40% from mV to 56 mV.

When an iron plate is used as the magnetic body 2 as described above, the iron plate has the advantages that it is inexpensive, easy to process and handle, and allows finer adjustment of the intensity of the bias magnetic field. As the magnetic material 2, an added magnet, cobalt, a compound of cobalt, nickel, or ferrite may be used.

The shape of the magnetic material may be arbitrary. Therefore, as shown in FIG. 2, the magnetic body 4 also surrounds the periphery of the magnet 1, as shown in FIG. 3, the magnetic body 5 is larger than the bottom surface of the magnet 1, as shown in FIG. The body 6 may have a shape smaller than the bottom surface of the magnet 1.

FIG. 5 shows a magnetic sensor in which magnetic members 7 and 8 are provided below the magnet 1 and between the magnetoresistive element 3 and the magnet 1. FIG. 6 shows a magnetic sensor in which a nonmagnetic material 10 is provided between the magnetoresistive element 3 and the magnet 1 instead of a magnetic material.

In these cases, as in the embodiment shown in FIGS. 1 to 4, the strength of the bias magnetic field applied to the magnetoresistive element is increased by providing a magnetic body below the magnet. In the embodiment shown in FIG. 5, by providing the magnetic body 8 between the magnetoresistive element 3 and the magnet 1, the strength of the bias magnetic field can be further increased. In the embodiment shown in FIG. 6, the strength of the bias magnetic field can be reduced by providing an interval made of the non-magnetic material 10 between the magnetoresistive element 3 and the magnet 1. In this way, finer fine adjustment of the resistance value and sensitivity of the magnetic sensor is possible.

In this embodiment, the case where the magnetic material is provided on the upper and lower portions of the magnet has been described. However, the present invention is not limited to this, and the magnetic material may be provided on the side surface of the magnet.

[0020]

As described above, according to the present invention, the strength of the bias magnetic field applied to the magnetoresistive element can be adjusted by providing a magnetic material in addition to the magnet. Therefore, fine adjustment of the resistance value and sensitivity of the magnetic sensor can be performed, and variation in the resistance value and sensitivity of the magnetic sensor can be reduced. In addition, the characteristics of the magnetic sensor that has been discarded because the resistance value and the sensitivity are out of the standard can be adjusted, and the yield can be improved.

As described above, according to the present invention, it is possible to provide a magnetic sensor whose characteristics can be adjusted by simple means when the resistance value and the sensitivity of the magnetic sensor vary.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a magnetic sensor using a magnetoresistive element according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a magnetic sensor using a magnetoresistive element according to one embodiment of the present invention.

FIG. 3 is a sectional view showing a magnetic sensor using a magnetoresistive element according to one embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a magnetic sensor using a magnetoresistive element according to one embodiment of the present invention.

FIG. 5 is a sectional view showing a magnetic sensor using a magnetoresistive element according to one embodiment of the present invention.

FIG. 6 is a sectional view showing a magnetic sensor using a magnetoresistive element according to one embodiment of the present invention.

FIG. 7 is a sectional view showing a magnetic sensor using a conventional magnetoresistive element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magnet 2 Magnetic body 3 Magnetoresistive element

Claims (2)

[Claims] 1. A magnetoresistive element, a magnet provided below the magnetoresistive element for applying a bias magnetic field to the magnetoresistive element, and adjusting the strength of the bias magnetic field provided in addition to the magnet. A magnetic sensor comprising: a magnetic body. 2. A magnetic sensor comprising: a magnetoresistive element; and a magnet provided below the magnetoresistive element for applying a bias magnetic field to the magnetoresistive element, wherein the intensity of the bias magnetic field is adjusted. A method for adjusting the characteristics of a magnetic sensor, comprising adjusting a magnetic field intensity applied to the magnetoresistive element by providing a magnetic material in addition to the magnet.