JPH0712905A - Magnetic sensor - Google Patents

Abstract

PURPOSE:To always enables accurate measurement of magnetic value regardless of the direction of a magnetic field using an electroconductive material for the sensing of magnetism. CONSTITUTION:An electroconductive material 1 is given a direction of motion with an exciting unit to perform an excitation. Sensor sections 1, 2 and 3 of a magnetic sensor are so arranged to be assembled to be vertical to each other and voltage signals obtained with the sensor sections 1-3 are subjected to a removal of high frequency portions with a filter circuit via an amplification circuit as required to obtain components in directions of intensity of a magnetic field of an object to be measured. For example, the intensities of the magnetic field separately in directions X, Y and Z are determined with the sensor sections 1-3. At a certain time, the voltage obtained with the sensor sections 1-3 is considered as components in directions (X, Y and Z) of intensity the magnetic field as the object to be measured and thus, the values of the intensities of the magnetic field as the object to be measured can be obtained by determining a sum of vectors.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic sensor for measuring the strength of a magnetic field.

[0002]

2. Description of the Related Art There are two types of sensor parts of conventional magnetic sensors: (1) a coil wound only (2) a coil wound around a dielectric such as a core.

However, the structure of (1) has a drawback of low reliability because it is inevitably large in shape, structurally weak and it is difficult to suppress variation in performance. Furthermore, this structure cannot be used as a current probe because the sensor has to make one round around the conductor whose current is to be measured.

Further, the structure of (2) is structurally improved by using a dielectric, as compared with the structure of (1).
It is possible to obtain a stable performance, and by adopting a structure in which the dielectric can be divided into two parts except when measuring, it has come to be used as a current probe, but the shape is further enlarged. It has the drawback of being Further, there is a problem that a high frequency magnetic field or its variation cannot be seen due to the restriction that the frequency characteristic of the dielectric is at most 0 to 1 MHz.

Further, in the conventional magnetic sensor, due to the structure,
The sensing direction of the coil or core, which is the core of the sensor, is limited to one direction, and accurate measurement cannot be performed unless the direction of the magnetic field emitted by the measured object and the sensing direction of the sensor are exactly the same. .

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and a conductive magnetic sensor having a structure different from that of the conventional dielectric magnetic sensor is provided. It is intended to realize stable and uniform sensor performance, miniaturization of the sensor, high reliability by simplification of the structure, and realization of a magnetic sensor having no directivity.

[0007]

The structure of the present invention for solving the above-mentioned problems is, in a magnetic sensor for measuring the strength of a magnetic field, a sensor section in which a moving conductive material and a conductive material move in the conductive material. Is provided, and two output terminals drawn from the conductive material are provided. In addition, it is characterized in that the three sensor parts of the magnetic sensor are combined and arranged so as to be perpendicular to each other.

[0008]

According to the present invention, the magnetic sensor is constructed so that the magnetic quantity can always be measured accurately by using the conductive substance instead of the coil for the magnetic sensing, regardless of the direction of the magnetic field.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a principle configuration diagram of a magnetic sensor of the present invention. In FIG. 1, reference numeral 1 is a conductive material, 2 is an excitation unit that gives the conductive material 1 a motion as shown by an arrow, and 3 and 4 are two output terminals drawn from the conductive material 1.

In such a structure, when the electroconductive substance 1 is excited and put in a magnetic field, a potential difference is generated in the electroconductive substance 1. This point will be described first in order. First, the exciting unit 2 gives the conductive substance 1 a direction of motion as indicated by a dashed arrow in FIG. 1 to excite it. It should be noted that, for simplification of explanation, the displacement of the motion is treated as a sine wave.

Here, the displacement of the conductive material 1 is shown in a simplified manner in FIG. In FIG. 2, the end point on the opposite side of the fulcrum O is a point S, the frequency of the sine wave motion is f ₀ , the length of the conductive substance 1 is a unit length “1”, the amplitude of the motion is A ₀ , and the fulcrum is the fulcrum. A is the amplitude of the motion at a point P at a distance p (0 <p ≦ 1) from O
_{Let p} .

It is assumed that the displacement of the conductive substance 1 is in the state of FIG. 2A at a certain time. Here, when the amplitude of motion A ₀ << 1, the displacement of the conductive substance 1 is approximated to FIG. This is because, when actually trying to move at a high frequency, the amplitude must be reduced and can be considered under this condition. At this time, A _p = p × A ₀ .

Next, the displacement of the point S at time t = 0 is 0.
Then the displacement A of the point S at a certain time t
_S (t) is given by the following equation. A _S (t) = A ₀ sin (2πf ₀ t) ... From this, the speed V of movement of the point S at a certain time t
_S (t) _{is, V S (t) = 2πf} 0 · A 0 cos (2πf 0 t) = A 1 cos (2πf 0 t) ...... However, it is A ₁ ≡2πf ₀ · A _0.

Therefore, similarly, the displacement A _{p at the} point P is
(T) and the speed of movement V _p (t) are A _p (t) = pA ₀ sin (2πf ₀ t) ... V _p (t) = pA ₁ cos (2πf ₀ t). Become.

Next, assume that a magnetic field H (magnetic flux density B) perpendicular to the motion vector of the conductive substance 1 as shown in FIG. 1 is applied. The electromotive voltage E (t) appearing between the output terminals 3-4 at that time is as follows. It is assumed that the magnetic flux density B = B ₀ (in the case of a DC magnetic field). Since it is a DC magnetic field, it is not necessary to consider the change over time. The electromotive voltage E (t) at this time is

[0016]

[Equation 1] Becomes

(At AC magnetic field) Magnetic flux density = B ₀ sin
(2πf ₁ t). The electromotive voltage E (t) at this time is

[0018]

[Equation 2] Becomes

Each electromotive voltage E (t) thus obtained
With respect to the above, by performing processing for removing high frequency components such as passing these signals through a low-pass filter, the following equation can be obtained. However, the frequency f ₀ >> f of the sine wave motion
_{Is 1} . (In case of DC magnetic field) E (t) = (1/2) · A ₁ B ₀ (In case of AC magnetic field) E (t) = (1/2) · A ₁ B ₀ sin (2πf ₁ t)

Therefore, first, a product obtained by multiplying the magnetic field applied to the conductive substance 1 by a certain constant {(1/2) A ₁ } may appear as an electromotive voltage between the output terminals 3-4. Obviously, it is possible to construct a magnetic sensor for measuring the strength of a magnetic field by using a conductive substance for magnetic sensing as in the present invention.

FIG. 3 is a block diagram showing an embodiment of the magnetic sensor of the present invention. Note that, in FIG. 3, the same elements as those in FIG.
In FIG. 3, (1) to (3) are sensor portions of the magnetic sensor shown in FIG. 1, which are arranged so as to be perpendicular to each other. In addition, the voltage signals obtained from the sensor units of to, if necessary, after passing through the amplifier circuit,
High frequency components are removed by the filter circuit. Thereby, each direction component (scalar) of the strength of the magnetic field of the measured object can be obtained.

In such a structure, the sensor units of to obtain the magnetic field strengths in the X, Y, and Z directions by the above-described methods. At a certain time, the voltages obtained from the sensor units are respectively E _X , E _Y ,
_Suppose it was E _Z. However, the gain from the sensing power to the end of filtering is always the same.
These voltages can be considered as the components (X, Y, Z) of the strength of the magnetic field to be measured in each direction. Therefore, by obtaining the vector sum of the respective vectors as shown in FIG. 3, the magnitude of the magnetic field strength to be measured can be obtained.

[0023]

As described above in detail with reference to the embodiments, the magnetic sensor of the present invention (1) does not require a coil or core, so that the size can be reduced. (2) It is not necessary to open the core and pinch an object to be measured such as a cable when measuring an electric current, unlike the conventional clamp meter. (3) If the work of removing the high frequency component (vibration frequency of the conductive material) is performed, by increasing this vibration frequency, a magnetic sensor having a frequency characteristic far superior to the frequency band of the current magnetic sensor can be obtained. Easy to implement. Further, in the conventional magnetic sensor, the strength of the magnetic field could not be accurately measured due to the problem of directivity, but it becomes possible to capture the strength of the magnetic field three-dimensionally, so that accurate measurement is always possible. Like

[Brief description of drawings]

FIG. 1 is a principle configuration diagram of a magnetic sensor of the present invention.

FIG. 2 is a diagram showing a displacement of the conductive material of FIG.

FIG. 3 is a configuration diagram showing an embodiment of a magnetic sensor of the present invention.

[Explanation of symbols] 1 Conductive material 2 Excitation unit 3, 4 Output terminal

Claims (2)

[Claims] 1. A magnetic sensor for measuring the strength of a magnetic field, the sensor part of which is a moving conductive material, an exciting unit for giving a motion to the conductive material, and two outputs derived from the conductive material. A magnetic sensor having a configuration including a terminal. 2. The sensor unit 3 of the magnetic sensor according to claim 1.
A magnetic sensor characterized in that the two are arranged so as to be perpendicular to each other.