JP2003130933A - Magnetic sensor element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic sensor element usable effectively for a self- holding magnetic sensor which can reproduce its former state, when power is supplied again even after a power-off. SOLUTION: This magnetic sensor element is comprised of a magnetic reluctance element, a bias magnet, and magnetic materials. In the magnetoresistive element, magnetoresistive patterns of ferromagnetic thin films are bridge- connected in approximately-perpendicular directions. The bias magnet is fitted onto the magneto-resistive element so that a magnetic field is applied in a direction of an angle approximately 45 degrees to any of the magnetic reluctance patterns. The magnetic materials having coercive forces of 1,000 to 3,000 A/m are arranged near sides of the magnetoresistive element in a direction perpendicular approximately to the direction of magnetic poles of the bias magnet.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic proximity switch, and more particularly to a magnetic proximity switch for origin detection in reciprocating operation.

[0002]

2. Description of the Related Art Conventionally, a latch circuit, a latching relay or the like has been generally used as a method for self-holding a detection signal of a proximity switch.

[0003]

However, the conventional method using the latch circuit or the latching relay has a drawback that the previous state cannot be reproduced when the power is turned off and then turned on again. The present invention has been made in order to deal with the above-mentioned drawbacks, and the number of components necessary for the self-holding operation is small, and even after the power is turned off without requiring the parts such as the latch circuit. When reapplying,
It is an object of the present invention to provide a magnetic sensor element used in a self-holding magnetic sensor capable of reproducing the previous state.

[0004]

In order to solve the above problems, according to the present invention as set forth in claim 1, a magnetoresistive element in which a ferromagnetic thin film magnetoresistive pattern is bridge-connected in a direction substantially orthogonal to each other, and the magnetic A bias magnet mounted on the resistive element so that a magnetic field is applied to any of the magnetoresistive patterns in a direction of an angle of about 45 degrees, and a magnetic pole direction of the bias magnet in the vicinity of a side of the magnetoresistive element. Provided is a magnetic sensor element in which a magnetic material having a coercive force of 1000 to 3000 A / m is arranged in a direction substantially orthogonal to. The present invention according to claim 2 provides the magnetic sensor element according to claim 1, wherein two or more magnetic materials are arranged with the magnetoresistive element interposed therebetween.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a magnetic sensor element of the present invention will be described below with reference to the drawings.

FIG. 1 is a structural exploded view of the magnetic sensor element of the present invention. The magnetoresistive element (101) is formed in a bridge shape so that each element of the magnetoresistive pattern (1011) is orthogonal to each other, and the magnetoresistive pattern (1011) is covered with a protective material.

The bias magnet (102) is mounted and fixed by epoxy resin or the like on the magnetoresistive element (101) so that a magnetic field having an angle of approximately 45 degrees is applied to any of the magnetoresistive patterns (1011). .

The magnetic material (1031, 1032) sandwiches the magnetoresistive pattern (1011) so as to be almost in contact with the bias magnet (102).
01) and fix with epoxy resin or the like.

FIG. 2 shows the magnetoresistive element (101), the bias magnet (102) and the magnetic material (1031,
The magnetic sensor element (200) integrated with 1032) is shown.

FIG. 3 is a diagram in which the magnetic sensor element (200) of FIG. 2 and the magnet (301) to be detected are arranged at an interval d, and the moving direction of the magnet (301) is indicated by an arrow. is there.

FIG. 4 shows the magnetic flux density with respect to the distance from the magnetic pole center in the direction perpendicular to the magnetic pole direction, with the distance (d) from the magnetic pole surface of the single magnet (301) to be detected in FIG. 3 as a parameter. On the other hand, the magnetic sensor element (2
FIG. 5 shows the detection output waveform of the magnet 00) for the detection target magnet (301).

In FIG. 5, even when the distance (X) from the magnetic pole center in the direction orthogonal to the magnetic pole direction of the magnet is sufficiently far, the magnetic sensor element output maintains a positive value on the positive X side,
On the negative X side, the magnetic sensor element output has a characteristic of keeping a negative value.

The magnetic sensor element output graph shown in FIG. 5 differs from the graph of FIG. 4 because a magnetic material is added to the magnetoresistive element with a bias magnet, which will be described in more detail below.

The output voltage waveform corresponding to FIG. 5 of the magnetoresistive element with a bias magnet when no magnetic material is attached is as shown in FIG. 6, and the magnet of the magnetic field generation source moves away regardless of the magnitude of the magnetic field strength in the middle. In either case, since the output approaches zero, the self-holding operation intended by the present invention cannot be performed as it is.

The operation when the magnetic material is attached so as to sandwich the magnetoresistive element with the bias magnet differs depending on the magnetic characteristics of the magnetic material.

(In the case of soft magnetic material) As shown in FIG. 7, due to the magnetic flux collecting effect of the magnetic material, the sensitivity is increased and the waveform rises sharply, but when the magnet to be detected moves away and the magnetic field becomes close to zero. Since the magnetization of the magnetic material becomes small, the output approaches zero, as in the case without the magnetic material, but the residual value of the magnetization depends on the coercive force, and becomes smaller as the coercive force is smaller.

(In case of hard magnetic material (material for magnet))
As shown in FIG. 8, it shows almost the same characteristics as when there is no magnetic material (FIG. 6). (Generally, hard magnetic materials for magnets (for example, ferrite) have an extremely large coercive force (130 KA /
Since it cannot be magnetized by an ordinary magnetized ferrite magnet or the like, it has a characteristic that magnetic material does not exist. )

(In the case of a magnetic material having an intermediate magnetic hardness) This corresponds to the case of the present invention shown in FIG. 5, in which the magnetic material to be magnetized is magnetized to the extent of an ordinary magnetized ferrite magnet, and Since it has an appropriate coercive force, the phenomenon that magnetization remains in the target magnetic material even if the magnetized ferrite magnet is moved away is used. The important point here is the practical operating distance (around 5 mm) between the magnet to be detected and the sensor.
Then, whether or not a magnetic material that operates can be selected.

FIG. 9 is a graph comparing the coercive force of various materials. From the graph of FIG. 4, a magnetic material operating at a magnetic flux density of 5 to 10 mT is taken into consideration when considering the magnetic flux density with respect to the distance from a practical magnet. Since it is necessary to select a magnetizing force of 2.5 times or more of the coercive force to magnetize the magnetic material, converting the magnetic flux density of 5 to 10 mT into an equivalent magnetizing force of 4000 to 8000 A / m. Therefore, 40% of this value is 1600 to 3200 A / m, and unless the material has a coercive force of less than this value, unstable magnetization cannot be used.

If the coercive force is too small, the magnetic field may be affected by the peripheral magnetic field to cause a malfunction such as magnetization reversal. Therefore, the coercive force is preferably in the range of 1000 to 3000 A / m. As such a magnetic material, as shown in FIG. 9, for example, S60C or SUS631 can be used. The material used in the embodiment of the present invention has a coercive force of about 1600 A in the graph of FIG.
/ M S60C.

[0021]

According to the magnetic sensor element of the present invention, a ferromagnetic thin film magnetoresistive pattern is bridge-connected in a direction substantially orthogonal to the magnetoresistive element, and the magnetoresistive element is formed on either of the magnetoresistive patterns. A coercive force of 1000 to 3000 A / in a bias magnet attached so that a magnetic field is applied in the direction of an angle of approximately 45 degrees, and in a direction substantially orthogonal to the magnetic pole direction of the bias magnet, close to the side of the magnetoresistive element. m
The magnetic material is arranged. Therefore, a component such as a latch circuit is not required, and the number of components required for the self-holding operation is small, and the power source O
It can be effectively used for a self-holding type magnetic sensor that can reproduce the previous state when re-input after FF.

[Brief description of drawings]

FIG. 1 is a structural exploded view of a magnetic sensor element.

FIG. 2 is a perspective view of a magnetic sensor element.

FIG. 3 is a perspective view of a magnetic sensor element and a detection target magnet.

FIG. 4 is a diagram showing a magnetic flux density in a direction orthogonal to a magnetic pole direction of a detection target magnet.

FIG. 5 is a diagram showing a magnetic sensor element output (related to the present invention) in a direction orthogonal to a magnetic pole direction of a detection target magnet.

FIG. 6 is a diagram showing a magnetoresistive element output with a bias magnet in a direction orthogonal to a magnetic pole direction of a detection target magnet.

FIG. 7 is a magnetic sensor element output in a direction orthogonal to the magnetic pole direction of the detection target magnet (for comparison with the present invention, the magnetic material is S
It is a figure which shows (when it is set as PCC).

FIG. 8 is a diagram showing a magnetic sensor element output in a direction orthogonal to a magnetic pole direction of a detection target magnet (when the magnetic material is ferrite for a magnet for comparison with the present invention).

FIG. 9 is a diagram showing coercive force by type of magnetic material.

[Explanation of symbols]

101 Magnetoresistive element 102 bias magnet 1011 Magnetoresistive pattern 1031 Magnetic material 1032 magnetic material

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Claims (2)

[Claims] 1. A magnetoresistive element in which a ferromagnetic thin film magnetoresistive pattern is bridge-connected in a direction substantially orthogonal to the magnetoresistive element, and a magnetic field is formed on the magnetoresistive element in a direction of an angle of about 45 degrees in any of the magnetoresistive patterns. Of a magnetic material having a coercive force of 1000 to 3000 A / m arranged in a direction substantially orthogonal to the magnetic pole direction of the bias magnet and a bias magnet attached so that a magnetic field is applied. Sensor element. 2. The magnetic sensor element according to claim 1, wherein two or more magnetic materials are arranged with the magnetoresistive element interposed therebetween.