JPS58218021A - Vertical magnetic head - Google Patents

Abstract

PURPOSE:To reduce the space loss of a reproduced output, by providing a soft magnetic core while sandwiching a gap of corresponding to about the shortest recording bit length and a medium running-out side face of a head core, in a vertical single magnetic pole head. CONSTITUTION:A magnetic flux 8 from a bit 6 of opposite phase adjacent to a bit 5 gives an interference to a magnetic flux 7 flowed from the bit 5. In providing a ''resolution core'' 9 of the soft magnetism acting a role absorbing this interference magnetic flux 8 via the single magnetic pole head 1 and a gap 10, the interference magnetic flux from the adjacent bit 6 is absorbed as 11 from the edge tip 9, and the spacing loss of the reproducing sensitivity of the single magnetic pole head is almost equal to that of a ring head. Since a wider gap (g) is not effective at the reproduction of a short wavelength and the too narrow gap short-circuits the magnetic flux between the adjacent bits at the reproduction and the shape of the magnetic field at the edge peak of the head is not sharpened at the recording, then the (g) is taken as about the shortest bit length.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the structure of a single-sided magnetic pole head that has a small space loss in reproduction output in a perpendicular magnetization recording system.

Compared to the conventional longitudinal magnetization recording method, the perpendicular magnetization recording method is clearly suitable for high-density recording because the magnetostatic energy of its residual recording magnetization state is more stable (the demagnetizing field is smaller). It is.

In order to apply this vertical method to rotary head VTRs and hard disks, the head structure must be operated from one side, rather than the auxiliary pole excitation type in which the medium is sandwiched from both sides. Next, in order to apply a deep, strong, and highly perpendicular recording magnetic field to the medium, it is necessary to use a single-pole head rather than a ring head. Thirdly, a recording/reproducing head is desirable in order to simplify the mechanism.

In order to satisfy the above three conditions, the present inventor provided a thick non-parallel single magnetic pole head with a highly saturated magnetized soft magnetic film in Japanese Patent Application No. 56-017224 and Japanese Patent Application No. 56-119903.

As shown in FIG. 1, by making the medium inflow end 2 of the single-pole head core 1 non-parallel to the medium outflow end 3 that forms the recording pattern, the inflow end of the time change of the magnetic flux from the medium recording pattern flowing into the core during reproduction is The fraction in can be made to even out and disappear due to the azimuth effect.

In the end, only the portion at the outflow end contributes to the reproducing voltage, so unlike the case of parallel single magnetic poles, the average thickness between the outflow end and the inflow end is 1/2 (t1+t
2) can be made thicker.

Therefore, it is possible to increase the magnetic flux flow transmission rate between the upper surface 4 of the single-pole head core in contact with the medium and the coil portion 5, which is necessary to increase the efficiency of recording and reproducing from one side.

A highly saturated soft magnetic film is provided on the media outflow side of the single-pole head core to sharpen the edge peak of the recording magnetic field and increase recording efficiency even on tapes with thin high magnetic permeability layers. It's for a reason.

The above-mentioned thick non-parallel single-pole head enables one-sided recording and playback, and its frequency characteristics are easy to use with no dip in the desired high-density region, but the playback space loss in the high-density region is large and the result is not as high as expected. High density characteristics could not be obtained.

In general, single-pole heads are worse than ring heads in terms of reproduction space loss, and therefore require extremely strict mechanical precision (particularly for floating heads), which has been a major obstacle to the practical application of the vertical method.

The present invention was made based on the results of a comparative investigation of the operation of a single magnetic pole head and a ring head to determine the cause of this problem. That is, to explain with reference to FIG. 2, the single magnetic pole head 1
The signal voltage induced in the coil 2 of the medium is due to the magnetic flux 7 flowing into the medium perpendicular recording layer 3 mainly from the recording magnetized bit 5 on the edge of the head. It is thought that the magnetic flux 8 from the adjacent bit 6 of the opposite phase, which is located away from the magnetic field, also flows into the sensitive edge tip, and 7 and 8 interfere with each other, lowering the reproduction sensitivity. Therefore, as a countermeasure, a soft magnetic "resolution core" 9, which serves to absorb the interfering magnetic flux 8 from the interfering neighboring bit, is connected to the single magnetic pole head 1 and the gap 1.
If bits 0 and 0 are placed apart, the interference magnetic flux from the adjacent bit 6 will be absorbed from the tip of the edge of bit 9 as 11, and the spacing (d) loss in reproduction sensitivity of a single magnetic pole head will be almost the same as that of a ring head. It should be. If the gap (g) is too wide, it will not be effective during short wavelength reproduction, and if it is too narrow, it will short-circuit the magnetic flux between adjacent bits 5 and 6 during reproduction, and the magnetic field break at the edge peak of the single magnetic pole head will not be sharp during recording. Therefore, it is optimal to set g to about the shortest bit length.

Although the above structure can be said to be like a ring head with an extremely wide back cap, its operation is essentially that of a single-pole head.

In order to demonstrate the effectiveness of this resolution core, we conducted an expanded reproduction model experiment. 1 cm in the model approximately corresponds to 1 micron (μ) in the actual head. However, the track width, thickness, and length differ from the actual proportions.

The materials of the single magnetic pole head 1, the resolution core 9, and the high magnetic permeability layer 4 of the medium are MnZn ferrite blocks, and the perpendicular recording layer 3.
is made by stacking Ba ferrite permanent magnets.

The sizes are as follows: Single magnetic pole head: t1 = 6.0cm t2 = 2.0cmW
=3.0cm L'=18.0cm Number of coil turns=50
0 resolution core: t3=1.0cm, L″=24.0c
mW = 3.0 cm, gap g = 0.5 cm (The shape and size of this model experiment are different from the operation explanation diagram 2, and an elongated rectangular parallelepiped was used.) Medium: Traveling length = 12 cm, Track width = 2.
5cm, perpendicular recording layer thickness=0.2cm bit length λ/2=
0.5 cm, high magnetic permeability layer thickness = 0.8 cm, spacing g = in the range of 0 to 1.0 cm, and the reproducing voltage when the medium passed was measured using a digital waveform memory. (Figure 3) Reproduction loss with only thick non-parallel single magnetic pole head = -50.6d/λ dB Reproduction loss with resolution core = -35.2d/λ dB In other words, space loss is improved by 15dB with resolution core. It was done.

As an example, a case will be described in which this structure is applied to a rotary head for a VTR. As shown in FIG. 2, this structure has a ring head shape with an extremely wide and long back gap, and since the known ferrite VTR head manufacturing method can be applied almost as is, only the different parts will be described.

First, as shown in FIG. 4, a single-pole head corresponding to one piece of the ring head is made using a single-crystal block 1 cut from a ferrite single-crystal ingot, and a highly saturated magnetic layer 2 made of, for example, Sendust, is applied to the abutting surface. Low nickel Fe-Ni
A thin film of about 0.0 mm by sputtering or vapor deposition of an alloy (permalloy) or an amorphous Co-IIIa to IVa metal alloy.
5μ (shortest bit length or less), and further thereon, as a gap layer 11, an Al2O3 or Cr metal thin film,
Approximately 0.5μ (less than the shortest bit length) is provided in a similar manner. After adhering to the resolution core, slice it along 12 to make a single magnetic pole head, so that the edge opposite to the gap side of the surface in contact with the medium is non-parallel to the depth number +
A micron scraper 13 is inserted so that the contact surface with the medium is approximately pentagonal.

Next, as shown in FIG. 5, a ferrite single crystal block 1 is manufactured as a resolution core manufacturing process corresponding to the manufacturing process of another piece of block with grooves for the coil hole of the ring head.
Groove 4 with a depth of about 0.3mm, gap depth 3 about 100mm
micron (D) and the rear end 5 (E D) required for precision bonding.
) and make a groove. Glass 6 is fused here,
After cutting the adhesive escape groove 7, this surface, which will be the abutting surface with the end magnetic pole head, is lapped to cover the glass portion and a highly saturated magnetized thin film 2 is provided in the same manner as in the single magnetic pole head.

The single magnetic pole part and the resolution core part are glued together, a coil hole 8 is made, and the rear end is cut off at 14 so that the magnetic path is not connected like a ring head, and then sliced, and the side surface is wrapped and the base is fixed.

The overall size is almost the same as a normal VTR head, with a medium running depth Ts Tr 1.5 mm and a width W = 0.15 mm.The track width after narrowing down is ~20 microns, but the In order to lower the magnetic field, the length L is set slightly longer to 3 to 10 mm.

This head can be used almost as is as a fixed head for floppy disks, audio PCM tapes, and computer tapes.

It can also be made smaller and attached to the rear end of a floating slider for a hard disk.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a thick non-parallel head with a highly saturated magnetized thin film (6). FIG. 2 is an explanatory diagram of the operation of a single magnetic pole head with a resolution core (9). 8 shows the interference magnetic flux when there is no resolution core. FIG. 3 shows the relationship between reproduction voltage and spacing in an enlarged model experiment (d is spacing, human is wavelength). 1 is with a resolution core, 2 is without a resolution core. FIG. 4 shows a method for manufacturing a single magnetic pole head core portion in a VTR head manufacturing process. FIG. 5 also shows the manufacturing method of the resolution core portion. 4 and 5, 1 is a single crystal ferrite, 2 is a highly saturated magnetized soft magnetic thin film, 3 is a gap depth, 6 is glass, 8 is a coil hole, 14 is a separation line after bonding, and the patent applicant Aki Otsubo■

Claims (1)

[Claims] A structure of a vertical single-pole head that records and reproduces information from one side of a medium, characterized in that a soft magnetic core is installed across a gap approximately equal to the shortest recording bit length from the medium outflow side of the head core.