JPS62192002A - Magnetic recording method - Google Patents

Abstract

PURPOSE:To prevent a bit of old information from mixing to a bit of new information, and to reduce the generation of a secondary distortion, by setting the angular shape ratio of a magnetic recording medium in a vertical direction below 0.6, and performing a preceding erase with a DC current. CONSTITUTION:An easy magnetizing shaft is prepared on the film plane of a magnetic layer in the vertical direction, and a magnetic head 12 is arranged facing with the magnetic layer of a recording medium 11 having the angular shape ratio of below 0.6 in the vertical direction. In the head 12, a recording and reproducing head 14 and an erasing head 15 are constituted in one body. In other words, a magnetic core 17 having a recording and reproducing gap 16, and a magnetic core 19 having an erasing gap 18 are constituted in one body by joining them interposing a spacer 20 made of a nonmagnetic material, and in a reproduction time, a reproducing output is taken out from the winding 21 of the recording and reproducing head 14. Since the gap width W2 of the erasing gap 18 is set larger than the gap width W1 of the recording and reproducing gap 16, and the gap length G2 of the erasing gap 18 is set enough larger than a recording and reproducing gap G1, no bit of old recording information is remained at a track side.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a magnetic recording method for recording signals using a magnetic recording medium such as a flexible disk, and particularly relates to a magnetic recording method that mainly records residual magnetization in a direction perpendicular to the film surface of the medium. This invention relates to a magnetic recording method for performing digital magnetic recording.

[Technical background of the invention and its problems]

In conventional digital recording, when updating recorded information, new information is simply overwritten on top of the old record.

However, perpendicular recording media suitable for ultra-high density recording have extremely poor overwriting characteristics. In other words, the old information is not completely erased and remains, which mixes into the new information as noise.

This is because in conventional longitudinal recording, the internal energy is maximum at the magnetization transition point, which is the information recording point, whereas in perpendicular recording, the energy is minimum and most stable at the magnetization transition point. be. Furthermore, in ultra-high-density recording, the gap between the recording and reproducing heads must be made extremely small in order to minimize reproduction loss, and as a result, magnetization cannot penetrate through the entire thickness of the recording medium, which also affects the overwriting characteristics. cause deterioration. In such so-called surface type recording, the permeation of magnetization changes significantly due to changes in the recording current between the drives, the gap length, the coercive force due to changes in the temperature of the medium, and the overwriting characteristics deteriorate.

As a method for solving this problem, a magnetic recording/reproducing device using a pre-erasing head has been proposed.

This proposal is characterized by arranging an erasing head at a position preceding the recording or recording/reproducing head in the traveling direction of the medium, and erasing the entire thickness of the medium in advance. However, subsequent experiments revealed that when the erasing current is set to direct current, as the degree of vertical orientation of the medium increases, second-order distortion of the reproduced signal increases, causing errors.

[Purpose of the invention]

The present invention was made in view of these problems, and
It is an object of the present invention to provide a magnetic recording method with good overwriting characteristics and with less occurrence of secondary distortion.

[Summary of the invention]

Based on the results of the experiments described below, this invention found that mixing of old information into new information can be prevented by setting the vertical squareness ratio of the magnetic recording medium to 0.6 or less and performing advance erasing using direct current. This was achieved by discovering for the first time that this method has low secondary distortion and is capable of high-density recording.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram for explaining a magnetic recording method according to an embodiment of the present invention. In the figure, the magnetic recording medium 11 is formed into a disk shape in this example, and has an axis of easy magnetization mainly perpendicular to the film surface of the magnetic layer, and the squareness ratio in the perpendicular direction is 0.6. It is as follows. The magnetic layer is formed by coating barium ferrite 1- on a substrate, for example.

A magnetic head 12 is placed opposite the magnetic layer of the magnetic recording medium 11 . The magnetic recording medium 11 has a magnetic head 12
It is assumed that the rotation occurs in the direction of the arrow.

13 is a recording track. The magnetic head 12 includes a recording/reproducing head 14 and an erasing head 15.
5 is placed at a position preceding the recording/reproducing head 14 on the magnetic recording medium 11.

FIG. 2 shows the magnetic head 12 in detail.

A recording/reproducing head 14 and an erasing head 15 are integrally constructed. That is, a magnetic core 17 having a recording/reproducing gap 16 and a magnetic core 19 having an erasing gap 18 are joined and integrated with a spacer 20 made of a non-magnetic material in between. Winding wires 21 and 22 are wound around the magnetic cores 17 and 19, respectively, and 21 and 22 windings are wound during recording.
A recording signal is supplied to the winding 22, and an iu erase current is supplied to the winding 22. During reproduction, the winding 21 of the recording/reproducing head 14
The playback output is taken from.

The gap width W2 (dimension in the track width direction) of the erase gap 18 is the gap width W of the recording/reproducing gap 16.

The gap length G of the erase gap 18 is set to above, and the gap length G of the erase gap 18 is
2 (dimension in the track length direction) is the recording/reproducing gap 16
The gap length G1 is set to be sufficiently larger than the gap length G1. W
Needless to say, the reason for setting □≧W2 is to prevent old recorded information from remaining on the track side due to head off-track or the like. Also, the reason for setting G2>G1 is to ensure that a sufficient erasing effect can be obtained, and since the erasing head 15 has no restrictions on recording and reproduction,
2 can be made sufficiently large. Also, G
If 2≦G1, the No. 42 magnetic flux detected in the erase gap 18 may cause a stroke in the timing core 17 of the recording/reproducing head 14, but if Q, >> Strokes can be sufficiently suppressed.

FIG. 3 shows experimental data on the relationship between the vertical squareness ratio and quadratic distortion after correction of the demagnetizing field of the magnetic recording medium. That is, for media with various perpendicular squareness ratios, each 10
10kFRPI while pre-erasing the magnetic recording medium with a DC erase current that attenuates the kFRPI signal to 140dB.
'I signal was recorded and the second-order distortion of the reproduced signal was measured. In addition, the experiment was conducted using a barium ferrite coated medium with an erase gap length of 2-1 and a recording/reproduction gap length of 0.
A 35 μs ferrite head was used. As can be seen from the figure, when the squareness ratio becomes 0.6 or less, the second-order distortion falls below the generally allowable -26 dB.

Figure 4 also shows a squareness ratio of 0.54 after vertical demagnetization field correction.
barium ferrite magnetic recording medium (magnetic layer thickness 3.0μ
s, vertical direction Hc = 750 oersted) using the device configured as shown in Fig. 1, there is almost no asymmetry caused by secondary distortion, etc., and the old information is below -40 dB. has been suppressed.

FIG. 5 shows the estimated cause of the difference in quadratic distortion due to the squareness ratio, which is the result of the above experiment. 4A shows the case where the perpendicular squareness ratio of the medium is small, and (b) shows the case where the medium has a large squareness ratio. When direct current erasing is performed using a magnetic head, for a medium with a small vertical squareness ratio, the magnetization vector is directed toward the energetically stable longitudinal direction as shown in FIG. 4(a). However, in a medium with a large squareness ratio, even when the head performs DC erasing, the magnetization buckle tilts in the vertical direction as shown in Figure 4(b).This is due to the high perpendicular anisotropy of the medium with a large squareness ratio. This is because sexual energy exceeds magnetostatic energy. On the other hand, with high-density recording, even if the vertical squareness ratio of the medium is relatively small, 0.5 to 0.6, the residual magnetization vector will be oriented in the vertical direction (1985 Institute of Electronics and Communication Engineers Semiconductor and Materials Division National In other words, in a medium with a small squareness ratio, the direction of the magnetization vector differs by 90 degrees between the erased state and the recorded state. Therefore, it can be inferred that the effect of erasure is less likely to appear as secondary distortion in the reproduced signal. On the other hand, in a medium with a large squareness ratio, the direction of the magnetization vector in the erased state and the magnetization vector of the recorded signal match, so it is expected that recording a signal on top of the erased state will result in an increase in second-order distortion. be done.

〔Effect of the invention〕

As explained above, according to the present invention, the old information that has already been recorded can be completely erased prior to recording, so that it is possible to prevent the old information from being mixed in as noise in the newly recorded information. High-quality, high-density recording can be achieved without distortion problems. It is desirable that the squareness ratio in the vertical direction be larger from the viewpoint of recording density characteristics, but it is
As is clear from 3), even with a squareness ratio of about 0.54, L
High-density recording of OOkFPRI or higher has been achieved, and considering the current value (approximately 9 kFPR for flexible disks), even a squareness ratio of about 0.6 is sufficient in terms of recording density.

Note that the present invention is not limited to the upper air embodiment,
Various modifications can be made without departing from the gist of the invention. For example, although the recording/reproducing head and the erasing head are integrally constructed in the embodiment, they may be constructed separately. Further, only the recording head and the reproducing head may be provided separately.

In that case, the erasing head only needs to be in a position preceding the recording head on the magnetic recording medium, and the positional relationship between the reproducing head and the erasing head is not particularly limited.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a schematic configuration of a magnetic recording and reproducing apparatus according to an embodiment of the present invention, FIG. 2 is a diagram showing details of a magnetic head section in the same embodiment, and FIG. 3 is a diagram showing various perpendicular square ratios. FIG. 3 is a diagram showing second-order distortion characteristics of a medium. FIG. 4 is a graph of an example of the characteristics obtained by the embodiment of the present invention, and FIG. 5 is an explanatory diagram showing the analysis results of the residual magnetization state examined from the results of FIG. 3. 11... Magnetic recording medium 12... Magnetic head 13
...Recording track 14...Recording/playback head 15
... Erasing head 16 ... Recording/reproducing head 17
...Magnetic core 18...Erase gap 19.
・Magnetic core 20 ・Nonmagnetic spacer 21 ・
... Recording/reproducing coil 22... Erasing coil agent Patent attorney Nori Chika Ken Yudo Kikuo Takehana Figure 1 Figure 2 Yuih! 4 peds 1 to j5

Claims (4)

[Claims] (1) In a magnetic recording method in which recording is performed mainly by utilizing residual magnetization perpendicular to the surface of the magnetic layer of a magnetic recording medium, the magnetic recording medium has a squareness ratio in the perpendicular direction of 0.6 or less after demagnetizing field correction. A magnetic recording medium is used, and an erasing head is placed on the magnetic recording medium at a position preceding the recording head or the recording/reproducing head, and a direct current is applied to this erasing head to erase old information, and then the recorded or A magnetic recording method characterized by recording new information using a recording/reproducing head. (2) The magnetic recording method according to claim 1, wherein the recording or recording/reproducing head and the erasing head are integrally constructed. (3) The magnetic recording method according to claim 1 or 2, wherein the gap width of the erasing head is greater than or equal to the gap width of the recording head or the recording/reproducing head. (4) The magnetic recording method according to any one of claims 1 to 3, wherein the gap length of the erasing head is greater than or equal to the gap length of the recording head or the recording/reproducing head.