RU1798744C - Device for measuring magnetic field - Google Patents

Abstract

Usage: in the field of measuring technology. SUMMARY OF THE INVENTION: The device comprises sensors. A feature of the invention is the connection of the sensors in series or parallel, which allows to expand the field of use by providing a measurement of the magnetic induction module. 1 C.p. f-ls, 4 ill.

Description

A magnetic field sensor is known, described in (Afanasyev Yu.P. Means of measuring magnetic field parameters. L. 1979), containing three magnetically sensitive elements (flux gates) that are mutually perpendicular in space, an excitation generator for ferroinduction converters and a processing circuit.

The aim of the invention is to expand the functionality of the device by providing module measurement, magnetic field induction.

1 shows a magnetoresistive element. Figure 2 shows the spatial arrangement of magnetoresistive elements and their subsequent electrical connection. In Fig.Z - shows the experimental dependence of the output. signal of a device with magnetoresistive elements made of germanium in a magnetic field during its rotation relative to two arbitrarily selected axes. Fig. 4 shows the same relationship for a device with magnetoresistive indium antimonide elements.

Consider the design of the device. It contains three identical magnetoresistive elements, one of which is shown in FIG. 1; The magnetoresistive region 1 has the shape of a rectangular parallelepiped, on the two opposite sides of which are applied the electrical contacts 2. Figure 2 shows the relative arrangement of the magnetoresistive elements in space. They are fixed on a common base in the form of a cube 4 so that each edge of the magnetoresistive region of each element is orthogonal to the edges of two other magnetoresistive ones. elements. The magnetoresistive elements shown in FIG. 2 are connected in series. It is also possible parallel to their connection. Magnetoresistive regions can be fabricated by applying ohmic contacts to semiconductor samples or formed in the channel of an MOS transistor.

To measure the magnetic induction module, the device should be placed in a magnetic field and its resistance measured. Under the influence of a magnetic field, the resistance of the magnetoresistive elements changes, so that the impedance of the device does not depend on the direction of the magnetic field. Moreover, for

ate

 Yu

At

4 4

SHAS &

one magnetoresistor made of an oligonductor material with an isotropic magnetoresistance effect can be written down (Weiss G. Physics of galvanic-magnetic semiconductor devices and x application, M., Energi, 1974.):

AR / R. +

where R is the resistance of the element. AR - its change in magnetic field; AT; - components of the vector of the AgN induction induction in the coordinate system, connected with a magnetoresistor; a, f, y, are coefficients depending on the material and geometry of the magnetoresistive region. As you can see, the resistance has a quadratic dependence on the components of the vector b. Bearing in mind that the magnetoresistive elements are located in space as shown in figure 2, for them can be written:

A.Ri / Rt aBx2 + / 3 BzV. ..

AR2 / R2 “By + / Bzft + y Bx,

ARs / R3 «Bz2 + / Bxr: +. at By2,.

Herein, indices 1, 2, and 3 are used to number the magnetoresistive elements. Since the elements are connected in series, the change in the resistance of the entire device is equal to the sum of the changes in the resistance of its elements, taking into account that the magnetoresistive elements are the same, i.e. Ri R2 R3, we get: A R / R () (Bxz + By + Bz1) (a + / 3 + y-) B2. .;. ... - :: .. .-. -. ,

As can be seen from the formula, the change in the resistance of the device is proportional to the square of the magnetic field induction module and not. depends on the direction of the induction vector. .: - /.,. : -; ,.

It is easy to show that when the magnetoresistive elements are connected in parallel, the magnitude of the induction module can also be determined from the conductivity measurements:. Dsg / cg - (a + / 3 + y) B2.,.

All the above-, calculations are made for magnetoresistive elements made of a semiconductor material with an isotropic magnetoresistance effect (for example, antimonide

INDIA);. ;, ...:.; .- - :. ,:

; In the case of using a semiconductor material of a cubic syngony, the magnetoresistance is non-isotropic and is described in general terms by the Seitz equation

(Smith R. Semiconductors. M., Mir, 1982J. In this case, all of the above calculations are true only if the edges of the magnetoresistive region are oriented

along the axes 100 of a semiconductor material of cubic syngony. Thus, in the manufacture of a magnetoresistive element from a semiconductor material of cubic syngonium, it is necessary to orient the edges of the magnetoresistor along the indicated crystallographic axes.

Magnetoresistive. the elements were made of L-type germanium and had the shape shown in FIG. 1, a length of 2 mm, a width of 7 mm and a thickness of 0.5 mm. The resistivity of the material is 10 Ohm "cm, the magnetoresistive elements were glued onto a cube of fluoroplastic, as shown

figure 2. The resistance of the device was measured with a V7-34A device in the ohmmeter mode. The total resistance of three series-connected magnetoresistors was 132 Ohms in the absence of a magnetic field, In a magnetic field. The resistance changed with a coefficient of 20 Ohms / T. The measured value of the magnetic field induction module B with an accuracy of 2 percent did not depend on the orientation

induction vector (see Fig. 3H).

In addition, the prototype of the proposed device was made on magnetoresistors made of n-type indie antimonide with a resistance of about 20 milliohms

 each. Magnetoresistors measured

respectively 2 mm, b 8 mm, s 0.5 mm. A constant current of 1 A was passed through the device, and the voltage drop across three series-connected magnetoresistors was measured with a B7-34A device in a voltmeter mode. The results are shown in figure 4. In this case, the measured value of the magnetic field induction modules with an accuracy of 3% did not depend on the orientation of the sensor in

magnetic field.

The proposed device is favorably characterized by the simplicity of the design, which is achieved due to the rejection of complex electronic signal processing.

Claims (2)

.. The claims 1, A device for measuring a magnetic field containing three magnetically sensitive elements, which are made in the form of rectangular magnetoresistors from of a semiconductor material with an isotropic effect of magnetoresistance or of a semiconductor material of a cubic syngony with an anisotropic effect of magnetoresistance so that the ribs are oriented along the axis 100 of the crystal, and which are arranged in space mutually perpendicular to each other, and the measuring unit, which differs in that, for the purpose expanding the scope of use by providing measurements of the magnetic induction module, magneto-sensitive elements are connected in series, and the measuring unit k is made in the form of a resistance meter. 2. The device according to claim 1. characterized in that the magnetically sensitive elements are connected in parallel, and the measuring unit is made in the form of a conductivity meter. 60 720 NoSopoma 4-- . W No. ite3 hell 360