SU570094A1 - Device for measuring gap between magnetic record carrier and magnetic head surface - Google Patents

Description

The winding of the head 13 is connected to the source of the reference voltage 14. The input of the selective amplifier 15 is connected with the photodetector 10, and the output is connected with a registrator. Bpock.,., .. Measurement of the firing is carried out between the working surface of the magnetic head 7 and the magnetic recording medium 17.

 $ GOSTROYSHOVO works 1 as follows:

: 3 the initial moment the value of saaopd S between the 1 and 13 head of the 13 and the magnetic recording medium 17 is 0. In the winding of the magnetic head 13 from the source of the reference voltage; 14, a postcurrent current is supplied, which in the magnetic core 7 generates a magnet of the head 13 and a magnetic current that magnetizes the magneto-optical element b to the reference LEVEL MOO. :.

The light from the source 1 but the optical fiber 2 hits the polarizer 5, it is polarized and then falls into the magneto-optical element, b. The plane of polarization of the light passing through the tepea magneto-optical element b turns with an angle fQP proportional to its magnetization, F. when the gap between the magnetic head 13 and the magnetic recording device is O, the polarization of the light passing through the magnetooptical element is set by the reference source 14. Next, through the optical fiber 3, the light hits the Faradator modulator € 1, case for module azimuth of the plane of polarization of light. For this, a harmonic signal of frequency W is supplied to the winding 11 of the Farad modulator of the harmonic generator 12.

As a result, those NC; The output from the Farad Modulator 8 azimuth of the plane of polarization changes in time according to the harmonic law. I Next, the light through the fiber 4 hits the analyzer 9i when the gap between the magnetic head 13 and the magnetic recording carrier is equal to the axis of maximum transmission of the polarizer: 5 and the analyzer 9 is set to; the angle ct satisfies the condition

..;,; .:

When the gap between the head and the carrier is equal to zero, the voltage of the double frequency is applied from the output of the photoreceiver 10 to the selective amplifier 15. {). The selective amplifier is tuned to the frequency W and therefore the voltage at its output is zero, which is recorded by the device 16.

With an increase in the gap between the magnetic head 13 and the magnetic recording medium 17, the shunt effect of the pg-last decreases, the magnetic resistance of the head-carrier circuit increases and the magnetization of the magneto-optical element 6 decreases.

As a result, the plane of polarization of light in the magnet-optic element 6: is rotated by an additional angle D. Magnetic dependence; the head resistance from, the gap between the head and the carrier in the interval of changes of the gap 0-10 micron is linear and the angle of rotation of the plane of polarization of light D is proportional to the size of the gap measurement (J, i.e. CfM.

When the gap between the magnetic head 13 and the magnetic recording medium 17 changes, the voltage OD, whose amplitude is proportional to the gap d, appears at the output of the photodetector Yu.

This voltage is amplified by the selective amplifier 15 and recorded by the recording device 16. By programming and recording the scale of the recording device in units of the distance between the magnetic recording medium and the surface of the magnetic head, the gap between them can be measured. The relative sensitivity and accuracy of measurements will increase due to the high accuracy and accuracy of registration — the angle of rotation of the plane of polarization of light .;

Accuracy of the registration angle. This light polarization is 0.00 p. The measurement accuracy of the G device is 0.6% compared with the prototype (40%), and the relative sensitivity is O, 15% / µm compared to the prototype (O, 0021% / µm ).

Claims (2)

1. A device for measuring the gap between the magnetic recording medium and the surface of the magnetic head, including a source of voltage, connected to the winding of the magnetic head, and a selective amplifier connected to the recording unit, characterized by the fact that, 1C channel, consisting of a light source, a polarizer, a magneto-optical element, a Farad modulator, the winding, which is connected to a harmonic signal generator, an analyzer and a photodetector nick connected optical fibers and the photodetector output is coupled to a selective amplifier, the magneto-optical element is part of the magnetic circuit of the magnetic head. 2. A device according to claim 1, characterized in that the magneto-optical element and the Farade modulator are made of a magnetically active crystal, such as yttrium ferrite garnet HozOts. Sources of information taken into account in the examination: . 1. US patent No. 3855584, CL, GH 15/62, publ. 1973. 2. R & D report Development, manufacture and supply of equipment for measuring the air gap to the rim by the working surfaces of the magnetic head and carrier, MIREA, All-Union Scientific, Technical and Information Center, 1INV. № В 346251. Th I in j IS one