SU957268A1 - Device for checking head unit - Google Patents

Description

(54) DEVICE FOR MONITORING MAGNETIC BLOCKS

one

The invention relates to instrumentation, in particular to magnetic heads used in magnetic recording apparatus.

A device is known in which a gadolinium gallium garnet strap with cylindrical magnetic domains is used as a sensor. The implementation of the control using this device is based on the fact that cylindrical magnetic domains are stable in a limited range of fields perpendicular to the film plane, and for noise exceeding the critical field Hct they collapse. An external magnetic system is used to create the field of His displacement. are seeking to destroy the domain structure. If the magnetic head gap field has a component. antiparallel to the displacement field, the cylindrical magnetic domains in the magnetic film exist only in the B region, the boundary of which is determined by the relation

Him - HK

Outside this area, the structure of the film will be destroyed fl.

The control of the working gap using the device described is rather complicated.

HEAD

It is also known to control the working gap of a magnetic head, which contains a light source, an optical system in the form of two crossed polaroids, a magneto-optical sensor, mounted in a cell with an optically transparent solution of ferromagnetic fluid, and a constant voltage source for powering the magnetic head 2.

The disadvantage of this device is 10 with the need to separately connect each head to the power supply in the process of control, which is inconvenient for multi-track blocks of magnetic heads. In addition, the device does not allow control of the skew angles in the dual blocks of magnetic heads and the distance between the pole tips in the multitrack blocks of magnetic heads.

The purpose of the invention is to simplify the process of controlling the size of the working gaps of magnetic heads and their mutual arrangement in the B block.

Claims (2)

The goal is achieved by the fact that the device for controlling blocks of magnetic heads, containing a light source, an optical system in the form of two crossed fields, a magneto-optical sensor, made in the form of a cuzette with an optically transparent solution of a ferromagnetic fluid, is equipped with an external magnetizing system oriented so that the plane the poles of its magnetic circuit are parallel or perpendicular to the base plane of the magnetic heads. FIG. 1 shows the proposed device with an external magnetizing system located parallel to the reference plane of the magnetic heads; in fig. 2 - the same, perpendicular to the base plane of the magnetic heads. The device contains a transparent-wall cuvette 1, which is filled with a solution of an optically transparent ferromagnetic fluid, magnetizing system 2, a light source 3 that creates a light beam 4, half-rays 5 and an optical indicator 6. A dual block of 7 magnetic heads containing a recording head 8 and reproducing The head 9 (FIG. 1) is located between the poles of the magnetizing system 2 so that the magnetic lines 10 of the magnetic field are directed parallel to the base plane of the magnetic heads. The monitoring of the working gaps of magnetic heads and their mutual arrangement in dual blocks containing recording and reproducing heads is carried out as follows. Magnetic heads 7 are placed in a cuvette 1 (Fig. 1) with an optically transparent ferromagnetic liquid so that the base plane of magnetic heads 8 and 9 is parallel to the line 10 of the magnetic field created by the external magnetizing system 2. When the magnetizing system is turned on in the zone of working gaps . a magnetic scattering field is created that changes the optical properties of the fluid. The light beam 4 from the light source 3 passes through the polaroid 5, a layer of ferromagnetic fluid in the cuvette 1, and is reflected from the working surface of the block 7 of the magnetic heads. The reflected beam again passes a layer of ferromagnetic fluid, the second polaroid 5 and is detected by an optical indicator 6, which can be used, for example, by any instrumental microscope. As a result of optical anisotropy, the linearly polarized beam undergoes a birefringence effect by the optical field 6. The dimensions of the area in which this phenomenon is observed characterize the critical zone of the working gap, and the accuracy with which the mutual th position of the magnetic Golobokov 8. 9, and the skew angle determined by the specifications of the optical indicator. FIG. 2, a multi-track magnetic tapehead unit 7 containing magnetic heads 8 is located between the poles of the magnetizing system 2 so that the magnetic lines 9 of the magnetic field are directed perpendicular to the base plane of the magnetic heads. The distance between the pole tips of the magnetic heads is measured in the following sequence. The magnetic heads unit 7 is placed B into the cuvette 1 with ferromagnetic fluid so that the base plane of the magnetic heads 8 is perpendicular to the lines 9 of the magnetic field created by the external - magnetizing system 2. The light beam 4 from the source 3 of the light passes through the polaroid 5, the magnetic layer fluids in cuvette 1 and after reflection from the working surface of the block of magnetic heads through the second polaroid 5. As a result of double refraction, a layer of fluid between the magnetobuds gleams. The distance between the plus tips is measured with the help of the negative indicator 6. The blocks of magnetic heads to be tested often have a diode that keep the heads very different in their parameters. For example, reproducing and recording heads, can be combined in one unit, and the use of an external magnetizing system simplifies the monitoring process, since it is not necessary to connect a voltage source to the contacts of the magnetic heads. In addition, the proposed device allows using the external magnetizing system to measure the distance between the working gaps of the magnetic heads, which cannot be determined by connecting a constant voltage source, since in this case the field is directed perpendicular to the working gap. Apparatus of the Invention The device for monitoring magnetic heads blocks, containing a light source, an optical system B in the form of two crossed fields, a magneto-optical sensor made in the form of a cell with an optically transparent solution of ferromagnetic fluid, due to the fact that, in order to simplify the process of controlling the size of magnetic heads and their relative positions in the block, it is equipped with an external magnetizing system oriented so that the plane of the magnetic poles is parallel or perpendicular to and the base plane of the magnetic head. Sources of information taken into account during the examination 1. USSR author's certificate No. 532126, cl. G 11 B 5/46, 1985. 2. USSR author's certificate number 593241, cl. G 11 B 5/46, 1976 (prototype).