JPS5912142B2 - magnetically sensitive element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetically sensitive element made of a ferromagnetic material that induces a steep pulsed electromotive force even in the presence of a minute external magnetic field.

As a magnetic wire that induces a pulsed electromotive force by an external magnetic field, what is known as a self-mononucleating magnetic wire has been known. This is done by subjecting the outer periphery of drawn ferromagnetic wire to cold heat treatment and work hardening treatment that applies external stress such as tension to form a relatively hard outer shell with high coercive force.
A relatively soft wire core called the core inside the outer shell is magnetically shielded by a hard outer shell. An external magnetic field is applied to this to magnetize the whole in one axis direction, and in the process of deenergizing the magnetic field, the magnetization direction of the soft core part is affected by the magnetization of the hard outer shell, forming a return magnetic path. This method utilizes the phenomenon of spontaneous reversal and induces a pulse output by the change in magnetic flux that occurs during the reversal, but the output is generally small and it is difficult to accurately control the point at which the pulse is generated. There are drawbacks. The magnetically sensitive element of the present invention is fundamentally different from such self-mononucleated magnetic wires in the magnetic properties of the magnetic wires themselves and the mechanism of generating electromotive force, and is stable even in the presence of a minute external magnetic field. It is characterized by the fact that a large pulse electromotive force is induced and the pulse generation point can be precisely controlled. The ferromagnetic wire constituting the magnetically sensitive element of the present invention has magnetic anisotropy as a whole, but unlike the conventional self-mononuclear magnetic wire described above, the wire core is hard and the outer periphery is hard. The parts have become soft.

In other words, the magnitude of the magnetic anisotropy changes continuously or stepwise from a relatively hard part of the interior to a soft part of the periphery, and preferably the soft part of the periphery is softer than the hard part of the inside. to cover. Therefore, it maintains a magnetically twisted state from the inner hard part to the outer soft part. Then, the superposition effect of the magnetization effect of the hard part with residual magnetism in one axis direction and the forced magnetization effect of the external magnetic field in the same direction becomes a trigger, rapidly changing the magnetization direction of the soft part. This allows translocation to . The process to induce the pulse electromotive force is as follows.

First, as a first step, a relatively large external magnetic field is applied to magnetize the entire hard part in a uniaxial direction.

Next, in a second step, a small magnetic field having a direction different from that of the external magnetic field is applied to magnetize the relatively soft portion in a direction different from or opposite to the axial direction of the first step. Then, in the third stage, when an external magnetic field to be detected with the same axial component as in the first stage is applied, this acts as a trigger to quickly and imperceptibly change the soft portion back to the magnetization direction of the first stage. transpose. At this time, the magnetic flux change that occurs in the magnetically sensitive element itself in the second and third stages induces a unique pulse-like electromotive force in the electric wire or coil arranged so as to interlink with this magnetic flux, and especially in the third stage. That is extremely remarkable. Moreover, if the magnitude of those magnetic fields is within an appropriate range, an electromotive force of a substantially constant magnitude can be repeatedly induced almost regardless of the time rate or speed of magnetic flux change. The magnitude of the detected magnetic field required to generate this electromotive force is a specific magnitude that can be determined by the coercive force and the magnitude of magnetic anisotropy energy that are pretreated in each part of the magnetically sensitive element. It is a magnetic field.

Furthermore, when a ferromagnetic wire is twisted in the circumferential direction around the wire core axis, or further twisted back in the opposite direction, or when such operations are repeated, the stress strain is fixed inside the wire. or can be left behind,
It is possible to configure a magnetically sensitive element having continuous or stepwise different magnetic anisotropy, in which the coercive force in the axial direction near the wire core is smaller and the residual magnetization is larger at the outer periphery. For example, a magnetically sensitive element made of an alloy mainly composed of iron and cobalt with vanadium added thereto is highly effective. Types of magnetic materials that can be applied to the present invention include Fe, N
Ferromagnetic alloys made of 1, CO, V, etc., and oxides or ferromagnetic mixtures thereof are preferable.

Next, the present invention will be explained with reference to the accompanying drawings.

When external stress is applied to a linear ferromagnetic material in opposite circumferential directions from both ends, a spiral torsional strain is applied toward the outer periphery of the line shown by the arrow in Al and A2 in Figure 1. The twist is smaller in the core portions A3 and A4. At this time, depending on the type of ferromagnetic material, a state can be created in which the magnetic anisotropy energy changes continuously or stepwise in the radial direction from the outer periphery to the core. Composition ratio is Homa F
Diameter 0.25mI1 Length approx. 407n7 made by drawing Bitskaroy of e5O%, CO4O%, VlO%! When observing the B-H characteristics of an untreated wire N of a ferromagnetic material of 4.t by applying a magnetic field in the direction of the wire axis, it shows hard characteristics with a relatively large coercive force.

Next, when we observe the treated wire T, which has been screwed and fixed two times in the circumferential direction around the wire axis, it exhibits extremely soft coercive force and residual magnetization, resulting in a significant change in magnetic anisotropy. obtain. Therefore, in order to clarify the magnetization state inside the wire, we sequentially observed it while etching it from the surface of the wire with diameter a.As shown in Figure 2, the coercive force Hc of the unprocessed wire N extends from the outer periphery to the core. The same hard characteristics (curve 10) are maintained. As shown by curve 11, in the treated line T, the coercive force Hc becomes smaller toward the outer periphery, and the residual magnetization B
As shown by curve 12, the value of r rapidly decreases from the outer periphery toward the inside of the line. This phenomenon of changing magnetic anisotropy occurs even when the wire is further twisted to leave a permanent twist, or even when the wire is twisted back and forth repeatedly to apply strain stress inside the wire and the wire appears untwisted. , its magnetic anisotropy can be maintained. In this case B
There is no problem even if the -H characteristic exhibits a meandering shape. The subsequent heat treatment at a relatively low temperature is effective in suppressing changes in shape and properties over time.
Now, an appropriate length of untreated wire N having a coercive force of about 40 oersteds is subjected to a process mainly consisting of twisting, so that the coercive force of the entire wire is made to be about 12 oersteds.

As shown in FIG. 3, a sensing coil 14 with a length of 2011 mm and a coil 15 with a length of Wind the coil. In this case, the two sensing coils are arranged so as to cancel the induced voltage caused by the external magnetic field. A relatively large first-stage external magnetic field is applied to previously magnetize the entire magnetically sensitive element configured in this way in the uniaxial direction of the arrow 16. Next, a relatively small second magnet is used to invert only the magnetization state of the relatively soft part.
A stepped external magnetic field is applied in the direction of arrow 17.

Once again, mark the arrow 1 on the magnetically sensitive element that has been prepared through the above process.
When a third stage magnetic field indicated by 8 having the same direction as the first stage and having a magnitude equal to or greater than the second stage is applied, an extremely steep pulse output is induced in the detection coil. If the change rate of the external magnetic field in the second and third stages is relatively small compared to the rotation of the magnetic spin of the magnetosensitive element itself and the speed of domain wall movement, for example, if the change is in the normal low frequency region, the coil 15 is not necessarily do not need. What is important here is that outputs are seen in the process of increasing the magnetic field shown by arrows 17 and 18, and that a unique pulse is generated in the process of applying the magnetic field in the uniaxial direction of the hard part, as shown by arrow 18. This is a phenomenon that occurs.

Also, when the magnetic field indicated by arrow 17 is small or not applied, arrow 1
Even if a magnetic field of 8 is applied, no unusual output is observed. Exactly the same output can be observed in these phenomena even when the direction of the magnetic field at each stage is reversed, and therefore the unique output at that time is large in the negative direction.

Such effects of the present invention are such that regardless of the length of the ferromagnetic wires constituting the magnetically sensitive element, most parts operate effectively based on the external magnetic field. The magnitude of the magnetic field is determined by the processing conditions during the formation of the magnetically sensitive element, but is also determined by applying a DC bias magnetic field of a predetermined magnitude to the completed magnetically sensitive element.

For example, as shown in FIG. 4, a method in which a current adjusted appropriately by a DC power supply 19 and a resistor 20 is passed through both ends of the magnetically sensitive element 13 to apply a bias magnetic field in the circumferential direction to the magnetically sensitive element 13. It is.

This is useful for controlling the magnitude of the external magnetic field at the time of output generation, and has the effect of reducing or eliminating the need for the magnitude of the second stage magnetic field.

If the polarity of the power source 19 is reversed, it is possible to induce pulse outputs of opposite polarity or of bipolar polarities with different magnetic fields at the time of output generation. Furthermore, in the process of forming the soft portion, interposing a layer having a coercive force of similar magnitude and direction and relatively uniform anisotropic energy has the effect of inducing an electromotive force with a large half-width.

The output can be increased by bundling the magnetic sensing elements of the present invention in parallel or connecting them in series. Moreover, depending on how the magnetic anisotropy is treated, output can be generated at different times in the magnitude of the applied magnetic field. Therefore, by appropriately combining them, it is possible to induce the electromotive force in a sequential or continuous output format, and it is also possible to obtain an electromotive force having a desired shape other than a pulse shape. When used in places where interference magnetic fields from outside are a concern, magnetic shielding may be applied to the outside of the detection coil of the magnetically sensitive element and the coil of the required working magnetic field. The magnetically sensitive element of the present invention having the above-mentioned performance can be used in a wide range of applications such as power system equipment, electric/electronic equipment, and measurement and control equipment.

For example, by applying the principles of the present invention to a power generator, or by appropriately setting a magnetically sensitive element to operate in the magnetic field generated due to an overload on a power transmission/distribution line, overcurrent protection devices, earth leakage circuit breakers, short circuits, etc. or ground fault relay, zero phase detector,
It serves as an operating signal generator for meter limiters and differential transformers, etc. It also provides means for quantitatively detecting the phase of single-phase, three-phase AC, etc., as well as phase rotation meters, frequency meters,
It can be applied to the configuration of tachometers, pulse torque meters, magnetic amplifiers, etc. Further, a non-contact switch, a synchronous or asynchronous pulse generator, a proximity switch, etc. can be constructed using the pulse output of the magnetically sensitive element of the present invention, either singly or in multiple configurations. In the engine ignition system, direction indicator, speedometer, and other signal sources associated with digital circuits used in automobiles, the magnetically sensitive element of the present invention inherently has cold and heat resistance characteristics and earthquake resistance. There are great ways to put it to use. In addition, the generated pulses are sequentially charged into a capacitor, and when the appropriate amount is reached, the transistors etc. are turned 0N and 0FF.
It can also be applied as a timed signal generator. By combining this capacitor charging method with several magnetically sensitive elements, a φ converter can be constructed. Moreover, not only can an A/D converter be constructed using several sets of magnetically sensitive elements set to operate according to the magnitude of an analog signal input, but also the output can be taken out as a coded signal via an encoder. If it is, it will be directly connected to the digital system as an input signal of the digital device. In addition, various logic elements in digital circuits, memory elements, magnetic recording elements, delay elements, shift registers, and magnetic card structures, as well as character tablets made by arranging the magnetically sensitive elements of the present invention in a matrix, etc. It can be applied to the configuration of new equipment. In any case, the unique electromotive force obtained by applying the magnetically sensitive element of the present invention can be generated without the need for any external energy such as a power supply, and is an outstanding product that can be generated quickly and reliably with an extremely high signal-to-noise ratio. It has many advantages, such as its relatively easy component configuration, high mass productivity, and the ability to provide it at low cost.

[Brief explanation of the drawing]

FIG. 1 is a tomographic diagram illustrating the internal state of the magnetically sensitive element according to the present invention, FIG. 2 is a graph illustrating observation results for explaining characteristics and phenomena, and FIGS. FIG. 2 is a principle diagram of a device constructed to extract output from a magnetic element. 13: Magnetically sensitive element, 14: Detection coil.

Claims (1)

[Claims] 1 Each part of the ferromagnetic material has a relatively hard and high coercive force that exerts residual magnetization in the uniaxial direction, but gradually changes to a softer part with a relatively small coercive force and high residual magnetization. The magnetization direction is controlled by an external magnetic field applied from the relatively soft side, and the magnetization direction of the relatively hard part maintains a magnetically twisted state. A magnetically sensitive element having an overall induced magnetic anisotropy that has been treated to allow.