JP2571755B2 - Magnetic recording / reproducing device - Google Patents

Description

The present invention relates to a magnetic recording / reproducing apparatus for perpendicular magnetic recording,
In particular, the present invention relates to a technology that enables high-density recording.

[Background of the Invention]

Conventionally, in a magnetic recording / reproducing apparatus for perpendicular magnetic recording, as described in JP-A-53-32009, a configuration in which a medium is sandwiched between a main magnetic pole and an auxiliary magnetic pole is disclosed in JP-A-54-51804. As described, the recording / reproducing is performed by a monopolar head on a double-layer recording medium in which a Co-Cr perpendicular magnetization film is provided on a high magnetic permeability layer, or the above-mentioned double-layer recording medium is used. , Main pole, Auxiliary pole Excited head for recording and ring head for playback (IEEE Trans on Magn. Vol Mag-17 (1981) 2
538) and others have been proposed.

100kBPI with an apparatus using a double-layered recording medium as described above
To achieve high-density recording of the order, for example, as described in the IEICE General Conference 1-197 of 1983, the main magnetic pole film thickness of the head was reduced to 0.15 μm, and the saturation magnetization Ms 500 emu / cc, Co-Cr medium film thickness of coercive force Hc400Oe,
0.3μm film thickness of the high permeability backing layer, respectively, configuration of a 0.6μm is appropriate, high-density characteristics of 110kBPI at a recording density characteristics D ₅₀ is obtained.

However, in the above-described apparatus, in order to improve the recording / reproducing characteristics of the head and obtain high reliability, Japanese Patent Application Laid-Open No. 52-14741
As described in JP-A No. 4 and JP-A-53-121608, it was necessary to make the shape of the head complicated.

JP-A-51-97415, JP-A-52-55513, JP-A-52-55513
The gap length as described in -82318 is large,
Also, in a perpendicular magnetic recording head having an asymmetric magnetic pole,
As described above, the shape of the head becomes complicated.

On the other hand, as described in the IEICE Technical Report MR81-8 (1981), when a single-layer film medium with large perpendicular anisotropy is used, good perpendicular recording is possible even with a ring head. It has been known. The ring head is different from the above-described single-pole type head, and is a head that has been used in actual devices so far, and its manufacturing technology has been established and its reliability is considered to be high.

As described above, many studies have been made on a perpendicular magnetic recording / reproducing apparatus using a ring head, which has a configuration in which a Co-Cr single-layer film medium and a ring head are combined.

In order to obtain high recording density characteristics in the device with the above configuration, it is necessary to use the MAG-83
As described in -39, thick Co-Cr with a thickness of 0.5 μm
It is necessary to adopt a method of recording on a single-layer perpendicular magnetization film medium with a special ring head with a gap length of 0.3 μm and a high saturation magnetic flux density of the head, and reproducing with a ferrite ring head with a gap length of 0.2 μm. Was.

The complicated configuration as described above is required for the following reasons.

In other words, in order to perform sufficient recording using a ring head on a Co-Cr single-layer film medium, it is necessary to increase the saturation magnetic flux density of the core material of the ring head to 1T or more and to increase the gap length to achieve a sufficient recording magnetic field. However, when reproducing from the recording medium using a ring head, the conflicting requirements that the gap length needs to be reduced in order to minimize the gap loss must be satisfied. Because.

Vol.1 of IEEE Trans on Magn. Vol MAG-18 (1982)
As described on pages 179 to 1181, when the medium thickness and the gap length are equal, analysis by computer simulation shows that in order to obtain a sufficient recording magnetic field, the medium must have a two-layer film structure. Good.

However, according to the same document, as far as the analysis by computer simulations is concerned, the reproduction output is improved by using a medium having a two-layer film structure, but the recording density (D ₅₀ ) at which the output is half of the maximum value is rather increased. It is clear that it will decrease. In addition, at the IEICE General Conference 1-203, 1983, the optimization of the parameters of each system by means of model calculation for an apparatus system that records on a double-layer film medium with a ring head was studied. It has been concluded that an apparatus combined with a layered film medium is not suitable for high-density recording because characteristics at high density deteriorate.

As described above, as a perpendicular magnetic recording / reproducing apparatus having particularly excellent recording / reproducing characteristics at high density, conventionally, a combination of a ring head and a single-layer film medium, a monopolar head, or a narrow gap asymmetric magnetic pole perpendicular magnetic recording It was thought that the combination of a head for recording and a two-layer film medium was appropriate,
Both of these configurations have the disadvantage that the head structure must be particularly complicated and the reliability is not very high. According to a simulation using a computer, an apparatus combining a ring head and a two-layer film medium is not particularly suitable for high-density recording.

[Object of the invention]

The present invention has been made to solve the above-mentioned drawbacks of the prior art, and has as its object to provide a magnetic recording / reproducing apparatus which is suitable for high-density recording, has a simple head structure, and has high reliability. And

[Summary of the Invention]

The present invention is particularly suitable for high-density recording and reproduction, and has been made by intensive experimentation with respect to a head medium system having high reliability. Even if a combination of a ring head and a two-layer film medium, which was considered unsuitable for reproduction, can be used as a high-density recording / reproducing device if the gap length of the head and the film thickness of the medium are selected in specific ranges. Is clarified experimentally.

That is, in the present invention, the gap length and the perpendicular magnetization film thickness of the ring head are each set to 0.25 μm or less, the recording magnetic field distribution in the medium is made steep, and the perpendicular magnetization film is lined with a high magnetic permeability layer. In addition to compensating for the decrease in the recording magnetic field strength due to the decrease in the gap length, the demagnetizing field also increases due to the decrease in the perpendicular magnetization film thickness, so that sufficiently efficient recording is performed.

According to experiments, the effect of the high magnetic permeability layer is remarkable when the relative magnetic permeability is 500 or more, and the magnetic properties of the perpendicular magnetization film are such that the saturation magnetization is 200 to 600 emu / cc and the vertical coercive force is 25.
If it is 0 to 1100 Oe, higher recording density can be achieved. At present, it is more preferable that the perpendicular magnetic recording medium is a Co—Cr thin film in terms of reliability, but the present invention is not limited to this.

The ring-type head used in the present invention is the same as a head which has been conventionally put to practical use except that the gap length is limited to a predetermined value or less. Therefore, a manufacturing technique is established and the reliability is high.

Note that the result of the present invention is different from the analysis result of the conventional calculation simulation because conventionally only the analysis of the head magnetic field was performed and the behavior of the medium that changes according to the head magnetic field was not considered. In fact, taking into account the magnetization process of the medium, a new simulation that comprehensively handles the ring head and the double-layered medium was newly developed and calculated, and the results of this experiment were qualitatively understood. We were able to. The reason why the experimental results are not quantitatively consistent with the experimental results is that it is extremely difficult to model a medium that matches the actual behavior of the medium, and it is extremely difficult to predict the experimental results in advance based on this. I can understand that

〔Example〕

 Hereinafter, the present invention will be described in detail based on examples.

FIG. 1 is a sectional view of an embodiment of the magnetic recording / reproducing apparatus of the present invention.

In FIG. 1, 11 is a ring type head, 12 is a coil,
Reference numeral 13 denotes a two-layer recording medium, 14 denotes a substrate of the recording medium, 15 denotes a high magnetic permeability layer, and 16 denotes a perpendicular magnetization film.

G is the gap length of the head, and t is the thickness of the perpendicular magnetization film.

Next FIG. 2 is a graph showing the relationship between the coercive force Hc⊥ the recording density characteristics D ₅₀ of the perpendicular magnetization film.

Note the D _50, the output of the output at low frequencies (1kBPI)
Indicates a recording density of 50%.

The characteristic shown in FIG. 2 is that the saturation magnetization is 350 emu as a perpendicular magnetization film.
/ cc, using a Co-Cr film with a thin film thickness of 0.2 μm, and a high magnetic permeability layer having a relative permeability of 800 at 1 MHz and a film thickness of 0.7 μm of Co-Z
Mn was added to the double-layer film recording medium using the r-Mo amorphous magnetic alloy thin film.
-Characteristics when recording and reproducing with a Zn ferrite ring type head.

Curve 21 shows the case where the head gap length g is 0.1 μm, curve 22 shows the case where the head gap length is 0.2 μm, curve 23 shows the case where the head gap length is 0.25 μm, and curve 24 shows the case where the head gap length is 0.3 μm.

As can be seen from FIG. 2, the characteristics are the highest when the gap length g is 0.2 μm, and the recording density characteristics D ₅₀ exceed 100 kBPI at 0.25 μm and 0.1 μm. , A decrease in performance was clearly observed.

Therefore, by setting the gap length g to 0.25 μm or less, high-density recording of 100 kBPI or more can be realized. The gap length may be as small as possible, but is preferably 0.01 μm or more for sufficiently efficient recording.

It can also be seen that high characteristics can be obtained when the vertical coercive force Hc⊥ is in the range of 250 to 1100 Oe. However, the demagnetization or overwrite characteristics of the medium (characteristics indicating the good performance of rewriting the initial signal when overwriting) is particularly 300 to 900 Oe
Was good.

When the gap length g shown by the curve 21 is 0.1 μm, the decrease in the recording density characteristic becomes sharp when the perpendicular coercive force Hc 大 き く increases, but this is due to the characteristics of the head used in the experiment. If a head having a large magnetic flux density is used, a decrease can be avoided.

Next, FIG. 3 is a diagram showing the relationship between the thickness of the perpendicular magnetization film and the recording density characteristics. The characteristics shown in FIG. 3 are that a perpendicular magnetization film uses a Co-Cr film having a saturation magnetization of 300 emu / cc and a perpendicular coercive force Hc _{L of} 300 Oe, and a high permeability layer having a relative permeability of 1200 MHz at 5 MHz.
This is a characteristic in the case where recording / reproducing is performed with a Mn-Zn ferrite ring type head on a double-layered medium using a 1.5 μm-thick Co—Zr—Nb amorphous magnetic film.

The curve 31 has a head gap length g of 0.07 μm, the curve 32 has a thickness of 0.2 μm, the curve 33 has a length of 0.25 μm, and the curve has a length of 0.35 μm.
The case of is shown.

As can be seen from FIG. 3, when the head gap length g and the medium film thickness t are 0.25 μm or less, high-density recording of 100 kBPI or more can be realized. Further, when the medium thickness t is 0.
It can also be seen that when the thickness is 25 μm or less, the smaller the gap length of the head is, the more excellent the recording density characteristics are, even with the same film thickness.
The medium thickness may be as small as possible, but is preferably 0.01 μm or more in order to obtain a sufficient reproduction output.

Next FIG. 4 is a graph showing the relationship between relative permeability μ and the recording density characteristics D ₅₀ of high magnetic permeability layer.

The characteristic shown in FIG. 4 is that the saturation magnetization of the perpendicular magnetization film is 300 emu.
/ cc, Co-C with thickness t of 0.15μm and vertical coercive force of 400 Oe
Using a film, Ni ₈₁ -Fe _{19 having a} film thickness of 1.5 μm as a high magnetic permeability layer
A gap length of 0.25 for a two-layer film recording medium using an alloy thin film
This is the characteristic when recording / reproducing with a ring head made of Ni-Zn ferrite of μm.

As can be seen from FIG. 4, the relative magnetic permeability μ of the high magnetic permeability layer is 50
It is understood that high density recording of 100 kBPI or more can be achieved when the value is 0 or more.

Next FIG. 5 is a graph showing the relationship between the saturation magnetization Ms of the perpendicular magnetic film and the recording density characteristics D _50.

The characteristic shown in FIG. 5 is that the thickness t of the perpendicular magnetization film is 0.25 μm.
m, a Co-Cr film having a vertical coercive force Hc⊥ of 500 Oe, and a high permeability layer having a relative permeability of 5000 and a film thickness of 1 μm.
The characteristics when recording / reproducing with a ring type head made of Mn-Zn ferrite single crystal on a two-layer film recording medium using an Nb amorphous alloy thin film are shown.

Curve 51 has a gap length g of 0.15 μm and curve 52 has a gap length of 0.15 μm.
The curve 53 shows the characteristics at 2 μm and the curve 53 at 0.25 μm.

As can be seen from FIG. 5, the saturation magnetization Ms of the perpendicular magnetization film is 20
In the range of 0 to 600 emu / cc, the gap lengths are 0.15 μm and 0.2 μm.
m, the recording density characteristic exceeds 100 kBPI and 0.25μ
In the case of m, although Ms is in the same range as described above, good characteristics are exhibited, although the overall decrease is slight.

Therefore, the saturation magnetization of the perpendicular magnetization film is preferably in the range of 200 to 600 emu / cc, and particularly in the range of 250 to 400 emu / cc.

In addition, a Co-Zr-W amorphous alloy thin film having a relative magnetic permeability of 2,000 as a high magnetic permeability layer using a Co-Cr film having a thickness t of 0.2 μm and a perpendicular coercive force Hc⊥ of 700 Oe as a perpendicular magnetic film. The same characteristics were obtained when recording and reproduction were performed on a two-layer film recording medium using a Mn-Zn ferrite ring type head having a gap length g of 0.2 μm.

Note that the above various characteristics are obtained by plating Co perpendicular magnetization film or Co-O
The same was true when the x perpendicular magnetization film was used.

〔The invention's effect〕

As described above, in the present invention, a combination of a normal ring-type head and a two-layer film recording medium, which has conventionally been considered impossible for high-density recording, is used, and the gap length and the film thickness are each 0.25 μm. By limiting to:
An excellent effect of achieving high-density recording as large as 0 kBPI or more can be obtained.

Further, since the ring type head and the double-layer film recording medium used in the present invention have been conventionally used in practice, the manufacturing technology has been established, and therefore, there is an advantage that the reliability is high.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of one embodiment of the magnetic recording / reproducing apparatus of the present invention, FIG. 2 is a diagram showing the relationship between the coercive force of the perpendicular magnetization film and the recording density characteristics, and FIG. 3 is the thickness and recording density of the perpendicular magnetization film. FIG. 4 is a diagram showing the relationship between the relative magnetic permeability of the high magnetic permeability layer and the recording density characteristics, and FIG. 5 is a diagram showing the relationship between the saturation magnetization of the perpendicular magnetization film and the recording density characteristics. Description of symbols 11: ring type head, 14: substrate 12: coil, 15: high magnetic permeability layer 13: double-layer recording medium, 16: perpendicular magnetization film

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hitoshi Nakamura 1-280 Higashi Koigakubo, Kokubunji City, Hitachi, Ltd. Central Research Laboratory Co., Ltd. 72) Inventor Sadao Hishiyama 1-280 Higashi Koigakubo, Kokubunji City, Hitachi, Ltd. Central Research Laboratory Co., Ltd. (72) Inventor Noboru Kumasaka 1-280, Higashi Koigabo, Kokubunji City, Hitachi Co., Ltd. 1-280 Higashi Koigakubo, Kokubunji City, Hitachi, Ltd. Central Research Laboratory Co., Ltd. (72) Inventor Nobuhiro Kudo 1-280 Higashi Koigabo, Kokubunji City, Hitachi Central Research Laboratory Co., Ltd.

Claims (6)

(57) [Claims] A thickness of 0.01 μm or more and 0.25 μm on the high magnetic permeability layer;
A magnetic recording / reproducing apparatus characterized in that recording / reproducing is performed on a double-layer recording medium provided with a perpendicular magnetic film having a length of not more than m using a ring type magnetic head having a gap length of not less than 0.01 μm and not more than 0.25 μm. 2. The perpendicular magnetization film has a saturation magnetization of 200 to 600 em.
2. The magnetic recording / reproducing apparatus according to claim 1, wherein u / cc and the coercive force in the vertical direction are set to values in the range of 250 to 1100 Oe. 3. The method according to claim 1, wherein said high permeability layer has a relative permeability of 500 or more.
Item 6. A magnetic recording / reproducing apparatus according to Item 1. 4. The magnetic recording / reproducing apparatus according to claim 1, wherein a Co—Cr thin film is used as said perpendicular magnetization film. 5. A magnetic recording / reproducing apparatus according to claim 1, wherein a plated Co thin film is used as said perpendicular magnetization film. 6. The magnetic recording / reproducing apparatus according to claim 1, wherein a Co-Ox film is used as said perpendicular magnetization film.