SU1204973A1 - Apparatus for measuring magnetic characteristics of magneto-rigid coatings - Google Patents

Abstract

The invention relates to magnetic measurements and can be used in determining the magnetic parameters of magnetic tapes or disks. The purpose of the invention is to improve the measurement accuracy and expand the functionality of the measuring device by eliminating the inconsistency of the measured magnetic field with the magnetic flux. The remagnetization coils 1 are connected opposite each other and in series with the measuring resistor 2 in the generator circuit 3. The measuring coil 4 in the form of a rectangular frame is located on the controlled sample 5 in the plane of symmetry of the system of coils 1 parallel to the windings of these coils, and the middle one from the sides of the measuring coil coincides with the intersection point of all three planes of symmetry of the system of coils 1. Measuring coil 4 through an integrating amplifier 6 is connected to the channel vertically deflection of the oscilloscope 7. The horizontal deflection last channel through the phase shifter 8 is connected to the measuring resistor 2. 2-yl. § (L with .f

Description

The invention relates to the field of magnetic measurements and can be used in determining the magnetic parameters of magnetic tapes and magnetic disks.

The purpose of the invention is to increase the measurement accuracy and extend the functionality of the measuring device by eliminating the inadequate measured magnetic field to the magnetic flux and providing a constant coefficient of flux ratio of the coating area with the measuring coil.

. 1 shows a structural diagram of the device, which shows the relative location of the measuring and magnetizing coils; Fig. 2 (a5 b), respectively, the distribution of the magnetizing field (at one of the times t) B of the plane of the turns of the measuring coil and the direction of the induction vector in the region of the magnetic coating located under the measuring coil,

A device for measuring magnetic characteristics of a magnetic field. Coatings (Fig. 1) consists of a pair of rectangular reversing coils 1S connected opposite each other and in series with the measuring resistor 2 in the generator 3 circuit of a periodic sequence of current different current pulses, the measuring coil 4, made in the form of a flat rectangular frame: on the controlled sample 5B, the plane of symmetry of the coil system 1p parallel to the winding planes of the windings of these coils, and the middle of one side of the measuring coil coincides with the intersection point of all three planes of symmetry of the coil system 1. Measuring coil 4 through the integrating amplifier 6 is connected to the channel of the vertical deflection of the oscillator 7, the channel of the horizontal 1313GO deviation of which through the phase shifter 8 is connected to the measurement - T ely 4y pesHcfopy 2. In FIG. 2 denotes a magnetic coating 9 and a non-magnetic base 10 of the region of the test sample, and also points 11-18 limiting the volume of the coating under the measuring cat ear.

2049732

The device works as follows.

A pulse current generator 3 generates a periodic sequence of current impulses of different polarity and coil 1 in a circuit consisting of the cathode 1 and the resistor 2 and a coil 1 - a non-uniform magnetic reversal field. The opposite switching of the same re-magnifying coils 1 leads to Tot-ry, that the components of the field normal to the plane of the windings of their windings in the plane of symmetry (the XZ plane) 5 where the measuring

15 coil 4 compensated. So

Thus, the total field in this plane does not have a normal component (figo 1, 5 - component Y), and in the absence of a controlled sample

20 5 the signal in the measuring coil 4 is missing. On the contrary, the components of the magnetic field reversal of the coils 1 lying in the plane of the measuring coil 4 are folded 25 s, while the fields of the left symmetrically located sides (figure 1) of the coils 1 give the total field on the X axis (perpendicular to the long sides of the coils 1) opposite to the cumulative field of the right symmetrically located sides of the coil 1. The total field on the X axis has only the X component. The corresponding distribution of the field on the X axis of the display 2 in Fig. 2a.

When placing sample 5 containing a magnetic coating, the plane: in: o, which is combined with the plane of the measuring cat-eye 4, direction

dd vector magnetic indukidi b in

the volume of the coating portion under the measuring coil 4 is as shown in FIG. 26. Consequently, by the Gauss theorem for a vector

jj of the magnetic induction into the field: the flux of this vector through the tightened-up surface is zero (FVFZ 0), then for the surface bounding the volume of the coating below the measuring point 50

carcass 4h represented by dots 11-14 in FIG. 25, have equality (the + sign indicates the flow, which follows from the volume under consideration)

55, (1)

where Ф, Фг ,, Фд, Фо, Ф are, respectively, in a B &W; POT-OKOV vector-R H B through the surface, denoted by

carcass 4h represented by dots 11-14 in FIG. 25, have equality (the + sign indicates the flow, which follows from the volume under consideration)

55, (1)

where Ф, Фг ,, Фд, Фо, Ф are, respectively, in a B &R;

points in 16; 12 13; 17; 15; eleven; 14 ; ,18; 18, 14; 13; 17; 15; eleven; 12; sixteen; eleven; 12; 13; 14.

As a result of placement of the measuring coil 4 in such a way that the middle of one of its sides coincides with the intersection point of all three symmetry planes of the remagnetisation node, the reversal field and, accordingly, the induction in the area of the measuring coil 4 practically do not change along the axis Z, and the value of the magnetizing field at the locations of the points 11 and 12 of the measuring coil 4 is zero at any time. From the induction homogeneity along the Z axis, it follows that ii, which, when substituted in (1), gives

.)

(2)

It follows from the equality to zero of the magnetization reversal field at the location of points 11 and 12 of the measuring coil 4 that the value of F0, which is the result of the residual magnetization of the test area before the measurement, does not change in the process of magnetization reversal and, therefore, does not contribute to the EMF ) ((t) of the measuring coil 4, Thus, the differential (2), for e get

. . „AF 1 .- AFD e ,, (t) N 2 AG

(3)

where N is the number of turns of the winding of the measuring coil 4. From expression (3) for the desired magnitude of the magnetic flux through the surface represented by points 18; 14; 13, - 17; get

4, (t) I j e (T) dC (4) o

The operation corresponding to equality (4) with an accuracy of the known constant multiplier R is realized in the integrating amplifier 6, the intensity of the reversing magnetizing field) in the section indicated by the points 18, 14, 13, 17, where the flux Fx (t) is measured, each time point is determined by the ratio

H Ct) R kn

(five)

where Uj (t) is the voltage across measuring resistor 2,

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R is the resistance of resistor 2;

k - calculated or measured constant,

5 connects the value of the field at points X x (Fig. 2b) with the current in the re-luminating coils 1. The field in the controlled area, the coating consists of external Hx, (t) and demagnetizing field due to the non-uniformity of the magnetization of the coating. However, in the case of a magnetically hard coating, calculations show that for typical values of the parameters of the coating and the distribution of the inhomogeneous magnetizing field, the magnitude of the demagnetizing field takes on the order of (0.1-0.2)% of the coercive force of the magnetic coating and therefore take into account. The signal from the output of the integrating amplifier 6 is fed to the input of the channel of the vertical deflection of the beam of the oscilloscope 7, and the signal

25 and (t) from the output of resistor 2 through phase shifter 8 is fed to the input of the channel of horizontal deflection of the beam of the oscilloscope 7. At the same time, the oscilloscope 7 records the dependence bd (H (,). For the calibration of the measuring channels in units of flow (channel of vertical deviation) and the field (horizontal deflection channel) serve as expressions (4), (5) taking into account the known kyij and the beam deflection factors in the corresponding channels of the oscilloscope. In general, the frame of the measuring coil 4 can be

Q is rotated at some angle around the Z axis with respect to the position shown in FIG. 1 and 26. At the same time, taking into account the small magnitude of the magnetizing field near X O and the small size of the measuring coil 4 in the direction of the Z axis (compared to the geometric dimensions of the re magnetizing coils), the increment of the flux Fo can also be neglected remagnetization field to determine in accordance with the ratio

55 ((6)

where is the angle between the normal to the point 18, 14, 13, 17 (Fig.26) and the axis X.

45

50

Comparing the obtained values of Ф,; (Н) 1) for different angles makes it easy to determine the nature of the anisotropy of the properties of the magnetic coating, in particular, to determine the direction of the axis of easy magnetization of the coating by the maximum value of the residual magnetic flux.

Formula of invention

A device for measuring the magnetic characteristics of magnetic-hard coatings, comprising an σ-magnetising unit, an alternator, a measuring coil made in the form of a flat rectangular frame, connected via an integrating amplifier to the oscilloscope’s vertical deflection channel, the input of which the horizontal deflection channel

through a phase shifter connected to a floor sensor, characterized in that, in order to increase measurement accuracy and expand the functionality of the device, the reversal unit is made as a pair of identical rectangular oppositely connected magnetizing coils, the planes of which are symmetrically parallel to the plane of the turns winding flat measuring coil placed on the test magnetic coating,

moreover, the middle of one of the sides of the measuring coil coincides with the intersection point of all three planes of symmetry of the magnetization reversal unit, and

A resistor connected in series is used with magnetizing coils in the current generator circuit.

but

Editor S. Lisin

Compiled by M. Klykova

Tehred I. Aotalos Corrector V.Sinitska

Order 8517/42 Circulation 747 Subscription

VNII1Sh State Committee of the USSR

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Branch PPP Patent, Uzhgorod, st. Project, 4

Claims (1)

Claim A device for measuring the magnetic characteristics of magnetically hard coatings, comprising a remagnetizing unit, an alternating current generator, a measuring coil made in the form of a flat rectangular frame, connected through an integrating amplifier to the channel of the vertical deflection of the oscilloscope, the input of the horizontal deflection channel of which is connected to the field sensor through a phase shifter, which differs the fact that, in order to increase accuracy, 5 measurements and expand the functionality of the device, the magnetizing block you it is complete in the form of a pair of identical rectangular opposite-connected magnetizing coils 10, the planes of which are located symmetrically in pairs with respect to the plane of the windings of a flat measuring coil placed on the test magnetic coating, 15 the middle of one of the sides of the measuring coil coincides with the intersection point of all three symmetry planes of the magnetizing magnetizing block, and as a field sensor 20 a resistor is used, connected in series with magnetizing coils in the current generator circuit .