JPS62204180A - Magnetic body detecting device - Google Patents

Abstract

PURPOSE:To securely detect the approach of a magnetic body to be detected by providing a nonmagnetic base which fixes the interval between a magnet and a large Barkhausen effect element and a detecting circuit which detects variation in the output pulse voltage of a detection coil and generates a signal. CONSTITUTION:At the time of the magnetic body 10 to be detected enters the DC magnetic field of a permanent magnet 5, the DC magnetic field produced by the magnet 5 is attracted by the magnetic body 10 to be detected which has specific magnetic permeability and the intensity of a DC magnetic field applied to an amorphous alloy wire 2 decreases in intensity, so the large Barkhausen effect of the amorphous allow wire 2 which is suppressed by the DC magnetic field increases again, so that the output pulse voltage of the detection coil 4 rises from a crest value V2 to t crest value V1. For the purpose, a detecting circuit 7 connected electrically to the detection coil 4 detects variation in the crest value of the pulse voltage and then the approach of the magnetic body 10 to be detected is detected from variation of the output pulse.

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention is a moving product counting, proximity switch.

The present invention relates to a magnetic body detection device that utilizes magnetic sensitivity with a magnetic body to be detected, which is used in a non-contact distance control device or the like.

[Prior art and its problems]

As a magnetic substance detection device using magnetic sensitivity, a Hall element is used when the magnetic substance to be detected generates a magnetic field, and a high-frequency induction device is used when the magnetic substance to be detected does not generate a magnetic field. Magnetic substance detection devices of the following type have been widely used in the past. However, the Hall element is expensive, and its characteristics change due to the influence of ambient temperature, so there are problems in that the structure becomes complicated, such as requiring a temperature correction circuit. In addition, in high-frequency induction detection devices, the flux emitted from the ferrite core interlinks with the magnetic material to be detected, causing eddying in the magnetic material to be detected, and this influence causes the oscillation circuit on the ferrite core side to Although this method detects the magnetic substance to be detected by stopping the transmission, it has drawbacks such as a complicated circuit configuration and a high processing cost for the ferrite core.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned situation, and an object of the present invention is to provide a magnetic body detection device that has a simple configuration, is not easily affected by ambient temperature, and is capable of stably and reliably detecting the approach of a magnetic body to be detected over a long period of time. With the goal.

[Key points of the invention]

Fe-based amorphous alloy wire, which is manufactured by ultra-quenching molten metal using spinning in a rotating liquid, has high magnetostriction and strong elasticity that retains the torsional residual stress that occurs in the surface layer during solidification. It becomes a soft magnetic material, and in an alternating current magnetic field, due to torsional residual stress in the surface layer, magnetization reversal occurs due to one instantaneous movement of the can wall, which is the so-called large Barkhausen effect, and the hysteresis loop exhibits a rectangular shape. A phenomenon called the so-called "Machiushi effect", in which a pulse voltage is generated between both ends of the amorphous alloy wire in synchronization with the instantaneous magnetization reversal, appears conspicuously, and if a detection coil is wound around the amorphous alloy wire, Instantaneous magnetic flux changes due to the large Barkhausen effect can be detected as sharp pulse voltages induced in the detection coil.

The present invention was made by focusing on the large Barkhausen effect of an amorphous alloy wire, and is made by winding an AC excitation coil and a detection coil around the outer peripheral surface of an amorphous alloy wire having high magnetostriction. A large Barkhausen effect element, a magnet that constantly applies a DC magnetic field between the large Barkhausen effect element and the orbit of the magnetic substance to be detected, and a non-emission base that fixes the distance between the magnet and the large Barkhausen effect element. When the stand is set up so that the magnetic substance to be detected does not approach, the direct current magnetic field applied to the amorphous alloy #J suppresses the large Barkhausen effect and reduces the peak value of the output pulse voltage of the detection coil. When the magnetic substance to be detected is close to the magnetic substance to be detected, the DC magnetic field is attracted to the magnetic substance to be detected, which has a high relative magnetic permeability, and the DC magnetic flux passing through the amorphous alloy wire decreases, resulting in a large bulk... The detection coil output based on the Uzen effect. Increase pulse voltage. In addition to making it possible to control the pulse voltage based on the so-called large Barkhausen effect, the change in the output pulse voltage is detected by a detection circuit and a signal is emitted. The magnetization of the magnetic field caused by the approach of the object is converted into an electrical signal, allowing stable and reliable detection.

[Embodiments of the invention]

The present invention will be explained below based on examples.

FIG. 1 is a schematic diagram showing a device according to an embodiment of the present invention.

In the figure, 1 is a large Barkhausen effect element, which is made of an Fe-based amorphous alloy @ (Fe77Si8B15) with a diameter of 0.12 m5+ and a length of approximately 30 mm, an AC excitation coil 3 which is AC excited by an oscillator 8, and a detection circuit. 7 is wound around a detection coil 4 which is conductively connected. In addition, in the figure, in order to make it easier to distinguish between the coils 3 and 4, the coils 3 and 4 are shown wound at different positions in the length direction of the amorphous alloy wire 2, but in reality Both coils 3.4 are wound around the outer peripheral surface of the amorphous alloy +11!2 over almost the entire length. Reference numeral 5 denotes a thin rod-shaped permanent magnet that is arranged parallel to the large Barkhausen effect element 1 with an interval of about several nanometers and fixed to a base 6 made of a non-magnetic material. By configuring the large Barkhausen effect element 1 and the permanent magnet in this way, the permanent magnet 5
is magnetically coupled with the amorphous alloy a2, allowing a considerable portion of the DC magnetic field generated by the permanent magnet 5 to pass through in the axial direction of the amorphous alloy wire 2, and also within the DC magnetic field of the permanent magnet 5. For example, when the detected maternal body 10 moving in the direction of the arrow on the trajectory 11 passing through the permanent magnet 5 is present at a distance of several orders of magnitude from the side of the permanent magnet 5, the direct current magnetic field generated by the permanent magnet 5 is compared. The direct current magnetic flux passing through the amorphous alloy wire 2 can be reduced by allowing a large amount of the magnetic material to be detected to pass through the magnetic body having high magnetic permeability.

A detection circuit 7 is conductively connected to the detection coil 4 and detects a change in the output pulse voltage of the detection coil to generate a signal.

FIG. 2 is a magnetization characteristic diagram in the above-mentioned embodiment device when no DC magnetic field is applied to the large Barkhausen effect element, and FIGS. 3 and 4 are diagrams when a DC magnetic field is applied in different directions. 3 is a magnetization characteristic diagram showing the hysteresis loop in the upper row, and the AC magnetic field H and the DC magnetic field Hd in the lower row.

Amorphous alloy? When no DC magnetic field is applied to fM2, the AC magnetic field H changes over time as shown in Figure 2.
Near the zero phase of the alternating current magnetic field H, where the change t (dH/dt) is large, domain wall movement due to the large Parkz-Usen effect and magnetization reversal occur instantaneously, and the hysteresis curve instantaneously changes between the positive and negative saturation values of the magnetic flux density. It shows a sharp corner that changes to . In addition, as shown in Fig. 3, a DC magnetic field Hd biases the AC magnetic field H of the amorphous alloy wire to the negative side (left side).
is applied and the DC magnetic field Hd is strengthened to near the peak value of the AC magnetic field H, magnetization reversal will occur near the positive peak value of the AC magnetic field H as indicated by a and b in the figure.
Since magnetization reversal occurs near the peak value of the AC magnetic field H where the AC magnetic field I (change 41 (dH/dt) is low, there is insufficient energy to cause the large Barkhausen effect,
The hysteresis curve has a shape biased toward the negative side where the magnetic flux density B does not reach the saturation value on the positive side. Furthermore, as shown in Figure 4, when a DC magnetic field Hd that biases the AC magnetic field H of the amorphous alloy wire to the positive side (right side) is applied, the magnetization reversal occurs as a negative wave for the same reason as mentioned above. This occurs at positions C and d near the high value, and the hysteresis curve has a shape in which the magnetic flux density B is biased toward the positive side.

FIG. 5 is a waveform diagram showing the pressure waveform of the output pulse ζ of the detection coil in the above-described embodiment in comparison with the AC magnetic field waveform of the large Parkz-Usen effect element, W11 is the AC magnetic field waveform, Wl2 is the second waveform. The output pulse voltage waveform corresponding to the magnetization characteristic diagram shown in the figure, Wl3, is the output pulse voltage waveform corresponding to FIG. 3, and Wl4 is the output pulse voltage waveform corresponding to FIG. 4, respectively. In the figure, the output pulse voltage waveform W12 of the detection coil 4 in a state where no DC magnetic field Hd is applied is generated every half cycle in synchronization with the vicinity of the zero phase of the AC magnetic field waveform Wll, and the hysteresis shown in FIG. Corresponding to the instantaneous change in magnetic flux density of the curve, the wave height value V is set in the production coil 4.

A large pulse voltage is induced. In addition, the transfer magnetic field [
When the DC magnetic field Hd close to the peak value of (2) is applied to the amorphous alloy wire 2, Wl 3. As shown in Wl 4, the output pulse voltage waveform of the detection coil 4 is generated on both sides of the peak value of the alternating current magnetic field H, and is caused by a decrease in the amount of change in the alternating current fi magnetic field near the peak value of the alternating current R and magnetic fields H. Due to the decrease in the large Barkhausen effect based on the
becomes smaller compared to That is, by combining the large Parkuts-Usen effect element 1 and the permanent magnet 5 that generates a DC magnetic field, the pulse voltage v2 induced in the detection coil 4 based on the large Parkuts-Usen effect can be changed to the same level as when no permanent magnet is used. It is possible to suppress the peak value to below v1.

Next, it is assumed that the magnetic substance IO to be detected approaches the detection device configured as described above along the trajectory 11 passing through the DC magnetic field of the permanent C+71 stone 5'. When the detected fa magnetic body 0 enters the DC magnetic field of the permanent magnet 5, the permanent magnet 5
The DC magnetic field generated by the detected magnetic body 1 with high relative permeability
0, the amorphous alloy i! i! Since the amount of the DC magnetic field Hd applied to 2 decreases, the large Barkhausen effect of the amorphous alloy wire, which was suppressed by the DC magnetic field t(d, increases T1 again, and as a result, the output pulse voltage of the detection coil 4 becomes It increases from the peak value v2 to the peak height @V1.Therefore, if a change in the peak value of the pulse voltage is detected by the detection circuit 7 connected to the detection coil 4, the magnetic body to be detected will be detected by the change in the output pulse voltage. 10 can be detected. Note that the magnetic body 10 to be detected must not be 8-shaped to the extent that it cannot attract the direct current magnetic field generated by the permanent magnet.

In the arsenic body detection device configured as described above, F
Since the e-based amorphous alloy wire does not cause any change in the large Barkhausen effect up to an ambient temperature of 150'CIX degrees, there is no need for a compensation circuit for changes in ambient temperature, and compared to the output pulse voltage based on the Machiusi effect, the detection coil It can induce a large pulse voltage, and its main components, the large Barkhausen effect element and permanent magnet, show little deterioration in later years and are simple and strong, resulting in a simple structure, long-term stability, and economic efficiency. A magnetic substance detection device can be obtained.

In addition, if the detection circuit is configured to, for example, set V2 as a threshold value and output a detection signal when an input signal exceeding V2 is input, it is possible to determine that the magnetic substance to be detected is close and output a detection signal. In addition, a proximity switch can be obtained by configuring the electrical contacts to open and close according to the detection signal, and furthermore, it can be used as a measurement cover for measuring the distance between the magnetic body to be detected and the permanent magnet and the pulse. By calibrating the relationship with the voltage peak value in advance, a wide range of applications can be expected, such as the creation of a non-contact distance sensor.

In the above-mentioned embodiments, the case where a permanent magnet is used as the magnet has been explained as an example, but the same function as the above-mentioned embodiment can be obtained even if a DC-excited electromagnet is used. Furthermore, by using a cured synthetic resin for the base 6 and embedding a large Barkhausen effect element and a hemorrhage in the base, a magnetic substance detection device that is mechanically strong and convenient to handle can be obtained. be able to.

〔Effect of the invention〕

As a result of the above-described configuration of the present invention, it is possible to control instantaneous shear wall movement and magnetization reversal due to the large Barkhausen effect, as well as the peak value of the pulse voltage induced in the detection coil, using the DC magnetic field generated by the magnet. By making it possible to control the direct current magnetic field applied to the amorphous alloy wire and the peak value of the pulse voltage induced in the detection coil due to the proximity of the magnetic substance to be detected, the principle differs from that of conventional technology. A magnetic substance detection device based on the present invention can be provided. In addition, the magnetization characteristics of the amorphous alloy wire do not change over time and have no temperature dependence at an ambient temperature of 150' CC variation, and a large pulse voltage can be induced in the detection coil due to the large Barkhausen effect, so the temperature compensation circuit It is possible to provide a magnetic body detection device that does not require any of the above, has a simple configuration, is inexpensive, has excellent handling convenience, and has stable detection accuracy over a long period of time. Furthermore, by devising a method for processing pulse voltage signals and output signals in the detection circuit, an advantage can be obtained that the present invention can be applied to a wide range of fields such as counting devices, proximity switches, and non-contact position sensors.

[Brief explanation of drawings]

Fig. 1 is a schematic configuration diagram of an embodiment of the device of the present invention, Fig. 2 is a magnetization characteristic diagram of the large Barkhausen effect element in the embodiment in a state where no direct current magnetic field is applied, and Figs. 3 and 4 are direct current FIG. 5 is a waveform diagram showing each output pulse voltage waveform of the detection coil in comparison with the alternating current magnetic field of the large Barkhausen effect element. DESCRIPTION OF SYMBOLS 1... Large Barkhausen effect element, 2... Amorphous alloy wire, 3... AC excitation coil, 4... Detection coil, 5...
...Magnet (permanent magnet), 6.. Base, 7.. Detection circuit, 10.. Magnetic body to be detected, 11.. Trajectory. Page [r@

Claims (1)

[Claims] 1) A large Barkhausen effect element formed by winding an AC excitation coil and a detection coil around the outer peripheral surface of an amorphous alloy wire having high magnetostriction, and this large Barkhausen effect element and a detected object. a magnet that constantly applies a DC magnetic field to the orbit of the magnetic body; a non-magnetic base that fixes the distance between the magnet and the large Barkhausen effect element; and a non-magnetic base that is conductively connected to the detection coil and provides an output pulse voltage of the detection coil. 1. A magnetic substance detection device comprising: a detection circuit that detects a change in the temperature and generates a signal. 2) A magnetic body detection device according to claim 1, wherein the magnet is a permanent magnet. 3) A magnetic body detection device according to claim 1, wherein the magnet is a DC electromagnet. 4) A magnetic substance detection device according to claim 1, wherein the base is made of a cured synthetic resin, and a large Barkhausen effect element and a magnet are embedded in the base.