JPS594669B2 - Magnetic field detection element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an element for detecting the magnitude and direction of a magnetic field.

Conventional magnetic field detection elements include search coils and Hall elements as main elements.

The former method detects an electromotive force that is proportional to the time change in magnetic flux passing through a coil according to the law of electromagnetic induction, but it has a serious drawback in that the detection sensitivity decreases as the time change becomes smaller. In that respect, the latter Hall element has the advantage of being able to detect even a DC magnetic field, but it requires a current terminal and a voltage terminal that produces an output proportional to the magnetic field, and the number of terminals is large, which tends to cause problems when attaching and removing the terminals. However, there are drawbacks such as the need for a driving current, and the unavoidable generation of heat and noise due to this. This invention was made to eliminate the drawbacks of conventional magnetic field detection elements as described above, and its purpose is to have sufficient sensitivity over a wide range from DC magnetic fields to AC magnetic fields, and to avoid heat generation and noise. An object of the present invention is to provide a high-performance magnetic field detection element in which the generation of magnetic fields is extremely reduced. That is, in this invention, a piezoelectric dielectric is sandwiched between conductive high permeability magnetic materials, and a Coulomb crab kanji generated by the magnetic charge on the end face of the magnetic material generated in a magnetic field is added to the piezoelectric dielectric and its polarization charge is detected. It consists of:

Furthermore, in the case where the direction of the magnetic field is also detected, the present invention is constructed by providing the above structure with a bias magnetic field generator at at least one end of the conductive high permeability magnetic material.

This invention will be explained below with reference to the drawings.

Figure 1 shows the basic configuration of the present invention, in which a piezoelectric dielectric material (titanic acid (lead zirconate, etc.) 3. If the dimensions a and b that determine the cross section in the shape shown in the figure are sufficiently smaller than the lengths 11 and 12 (for example, a2b250μm, l321225mm, and 210ttm), the Y direction Z shown in the figure Since the demagnetizing field coefficient increases in the direction, the magnetization components in the Y and Z directions become almost o, and the
Magnetizes only in the direction. Therefore, as shown below, such a magnetic field detection element selectively detects only the magnetic field component in the X direction. The magnitudes of magnetization M1 and M2 are proportional to the magnetic field H to be measured, and the magnetic bodies 1 and 2 have magnetizations of M and M per unit area at both ends of the magnetic bodies 1 and 2, respectively. Magnetic charges appear, and in particular, on the surface in contact with the piezoelectric dielectric 3, magnetic charges of opposite signs face each other, and pressure due to the Coulomb crab kanji (gravitational force) is applied to the dielectric 3. This pressure causes the dielectric body 3 to undergo electrical polarization, thereby creating a potential difference between the conductive high permeability magnetic bodies 1 and 2, which value is electrically detected through terminals 8 and 9 attached to each. be done. In other words, such an element responds only to the magnetization components of the magnetic bodies 1 and 2 that cause the Coulomb crab kanji, and therefore selectively detects the x component of the magnetic field to be measured, and generates an electrical signal according to its magnitude. Show the output. FIG. 2 shows another embodiment of the present invention, in which a bias magnetic field generator is added to the basic configuration shown in FIG. 1. That is, terminals 28 and 2
A piezoelectric dielectric material 23 sandwiched between conductive high permeability magnetic materials 21 and 22 marked with 9 and said magnetic materials 21 and 22
It consists of a bias magnetic field generator 24 that is magnetized in one direction in advance. The bias magnetic field generator 24 causes the magnetic body 21 to
and 22 are magnetized in advance in one direction (the negative direction of
00 Ersted. ) A constant pressure is applied to the piezoelectric dielectric 23 even when the magnetic field to be measured is O. When the magnetic field to be measured is in the same direction as the magnetic field generated by the bias magnetic field generator 24, the magnetic bodies 21 and 22 are magnetized by the sum of the two, and a stronger pressure is applied to the dielectric body 23. A larger potential difference is created between terminals 28 and 29. On the other hand, when the magnetic field to be measured is in the opposite direction to the magnetic field generated by the bias magnetic field generator 24, the magnetic field of the difference between the two is generated by the magnetic body 21.
Since the magnetization is applied to the terminals 28 and 22, the magnetization becomes smaller, the force applied to the dielectric 23 is reduced, and the potential difference generated between the terminals 28 and 29 is also reduced. In this way, the magnitude and direction of the magnetic field to be measured can be detected by the magnitude and increase/decrease of the potential difference generated between the terminals 28 and 29 with respect to when the magnetic field to be measured is zero. FIG. 3 shows an example of a current detector (forcelet probe) constructed using the embodiment shown in FIG.

A piezoelectric dielectric material 33 is sandwiched between conductive high permeability magnetic materials 31 and 32 to which terminals 38 and 39 are attached, respectively.
One end is connected to the bias magnetic field generator 34 via the high permeability magnetic bodies 35 and 36, and the generated magnetic field applies a constant pressure to the piezoelectric dielectric 34 (the path of the magnetic lines of force is shown by the dotted line in the figure). In addition to High permeability magnetic material 35
When the conductor 37 through which the current 1 flows is placed within this frame, the magnetic field generated around the conductor 37 is applied to this current detector, and if the direction is the same as the bias magnetic field, an output increase is generated between the terminals 38 and 39. , in the opposite direction will result in a decrease. The amount of change is a value corresponding to the current flowing through the conducting wire 37, and high-sensitivity current detection from direct current to high frequency becomes possible.

The materials mentioned in the above examples are merely examples for implementing the present invention, and the materials are not limited to the above-mentioned materials.

This type of magnetic field detection element requires only two terminals, and does not require an external supply of energy to drive it.
Therefore, it has the advantage of generating less heat and noise, and is particularly excellent in detecting minute magnetic fields (100 oersted or less).

[Brief explanation of the drawing]

1, 2, and 3 show examples of the present invention, in which 1, 2, 21, 22, 31, and 32 are conductive high permeability magnetic materials, and 3, 23, and 33 are piezoelectric 24 and 34 are bias magnetic field generators, 35 and 36 are high permeability magnetic materials, 37 is a conductive wire, and 8, 9, 28, 29, 38 and 39 are terminals. .

Claims (1)

[Scope of Claims] 1. A magnetic field detection element comprising a piezoelectric dielectric material and a conductive high permeability magnetic material sandwiching the piezoelectric dielectric material and fixed to both sides thereof. 2. A piezoelectric dielectric, a conductive high permeability magnetic material fixed to both sides of the piezoelectric dielectric, and a bias magnetic field generator fixed to at least one end of the conductive high permeability magnetic material. A magnetic field detection element characterized by comprising: