SU1672522A1 - Method of magnetic tape copying effect prediction by the magnetic properties of magnetic powder - Google Patents

Abstract

This invention relates to a magnetic recording technique, in particular, to methods for predicting the copy-effect of a magnetic tape. The aim of the invention is to improve the accuracy of the prediction of the copy effect in the range of sound frequencies according to the magnetic properties of the magnetic powder. The method is carried out as follows. A sample is made of the magnetic powder by orienting the magnetic varnish in the external magnetic field along the length of the sample and drying. After demagnetization, the residual longitudinal and perpendicular magnetic susceptibilities are measured and a copy-effect value is calculated using the proposed formula, which takes into account both susceptibilities and is valid in the range of sound frequencies.

Description

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The invention relates to a magnetic recording technique, in particular, to methods of predicting copyraffecc (EC) of magnetic tape, and can be used in the development of magnetic tapes with a chain of improved production efficiency, achieved by determining the CE by the properties of magnetic powder prior to the manufacture of magnetic tape.

The aim of the invention is to improve the accuracy of prediction of tape EC in the audio frequency range.

The method is implemented in a delayed manner.

From magnetic material, for example, magnetic material, is made about Oa with an arbitrary ratio of thickness and thickness in the external magnetic field of the magnetic varnish along the length of the sample, followed by pysiphonie. m directed along the length of the sample and extending over time t. The field Hx is 1525 kA / m chosen because this value has a copy field acting in a roll of tape (1) 6-10 s after turning off the magnetic field measure the residual th magnetic flux (sample S over the cross section perpendicular to the magnetic susceptibility field Hx in the longitudinal direction is determined from the relationship

A-F

Lz - - -

. But Hh S

After demagnetization, the device is placed in a magnetic field of Well, for example, with a value of 15 25 kA / m. perpendicular to the sample plane and valid for a period of time t After 6 South post1 the magnetic field switch tmg Cl of Titus accurate magnetic flux Φ, nj spark

ON XI

Yu

1SL

Yu

YU

samples 87 perpendicular to the field H,

The MLT of the perceptual susceptibility of the OM of the pNTICBODCHNPM direction is determined from the ratio

to - v /.to Well Sy

The expression for calculating the QE, valid for recording wavelengths that are much larger than the thickness of the working layer, has the form

tg d 2l (+ 0- KE-201d (kx + Ku) - d I

where D and d - the thickness of the base and the working layer; And the wavelength of the record. The boundedness (1) of wavelengths is due to the approximation of the expression used for the amplitude value of the copy field

Mk - Mo TdS1)

fair for d d (5), here M0 is the amplitude value of the magnetization in the original signaling signal: at the distance from the surface of the working layer. If for field copying use an expression that is valid for all recording wavelengths (6)

 2tl-- pa J

Nk -b / o1

year

R

M 7- G

(3)

then the expression for CE will take the form

 ., } one

(„Hx Sx // oHySy) 2

2 o

The copying time t is set in the relevant technical specifications.

From the magnetic powder used in the SWEEM software for the manufacture of the A4620 magnetic tape, a lacquer was made in a test tube, which was applied to a polyester film and dried in a magnetic field of 160 kA / m. The thickness of the magnetic layer is 38 microns. The process of making varnish. applying it to the film and drying takes about 2 hours. A sample with dimensions of 6x6 mm is cut out of the obtained sample, which is demagnetized in a razmahivivayuschey device This field is 24 hours. After turning off the field, the sample is placed in a vibrating magnetometer and its magnetic moment is measured. The sample is dimensioned and its magnetic moment is calculated, its residual magnetic flux is calculated. Then the magnetic nrv is calculated.

After the demagnetization of the sample, the magnetic susceptibility in the perpendicular direction of the Hu, Pol5 was determined in a similar way to X - 2.1 xH2, Hu - 0.4x102.

According to the technical documentation, the tape A4620 should have a working layer with a thickness of 16 µm and a base with a thickness of 39 µm, using the formula (4) description using

10 of the above data was calculated predicted value of CE - -57.5 dB. The measured value of the real A4620 tape is 56.0 dB

15One of the reasons for low accuracy

predicting the CE by a known method, the applicant is not counting the perpendicular component of the magnetization. In order to numerically determine the error arising from this, we put in the formula (4) only the value Хх. and Hu neglect. The calculation gives CE - -59.0 dB. That is, ignoring the perpendicular component of the residual magnetization leads to an additional error of -1.5 dB

If at the stage of development of a magnetic tape the predicted QE is worse than what is required, then this magnetic powder will be rejected and the tape will not be made of it.

thirty

Claims (1)

Claims A method for predicting a copy-tape magnetic tape on magnetic properties of a magnetic powder, including making a sample singing from a magnetic magnetic tape material, measuring the residual magnetic flux of a sample, and predicting a copy effect, , a sample with an arbitrary ratio of length to thickness is made by orientation of the magnetic varnish in the external magnetic field along the length of the sample, 45 applied to the substrate, followed by drying, after demagnetization, the sample is placed in a magnetic field H of intensity 1 5 2.5 kA / m, directed along the length of the sample and acting for a time 50 t, 6-10 s after turning off the magnetic field, the residual magnetic flux Fh is measured over the cross section of the sample St to the perpendicular field Ht. after demagnetization, the sample is placed in a magnetic field with a magnitude of 1.5 and 2.5 kA / m, which is directed perpendicular to the npi plane. and operating for a time t, 6 10s after switching off the magnetic field, the Ognosis mlnigunny flow F is measured (cross section 51R72522G, the sample of Sy, a perpendicular field of Well, - l + (M and copy-effect prediction magnet-h () Noi tape calculated by the formula where D and d are the thickness of the base and the working layer G / FhFu 15 magnetic tape; CE 20 Ig b; - + n s --J 3 k // O is the magnetic constant; L 1 / J - - rmntii t i n iji L i r riQfc l i wavelength of the recorded signal. - magnetic constant;   rmntii t i n iji L i r riQfc l i wavelength of the recorded signal.