JP2001023143A - Magnetic recording medium and method for recording/ reproducing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make constructible a high-density recording system by forming a magnetic layer on a nonmagnetic supporting body, and setting the product of the amount of residual magnetization and the film thickness of the magnetic layer, and the track pitch of recording tracks formed to the magnetic layer in a specific range. SOLUTION: The magnetic layer 2 of a metallic magnetic thin film is formed on a nonmagnetic supporting body 1, thereby constituting the magnetic recording medium. In the magnetic recording medium, the product Mr.t of the amount of residual magnetization Mr and the film thickness(t) of the magnetic layer is set to be 0.5-3.0 memu/cm2 and, the track pitch of recording tracks formed to the magnetic layer is set to be 1-5 μm. At this time, the thickness of the magnetic layer 2 can be controlled by changing a line speed in a thin film form apparatus, and the amount of residual magnetization can be controlled by changing an amount of oxygen introduced during the film formation. The product of the amount of residual magnetization and film thickness of the magnetic layer is specified by controlling the two parameters desirably.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium having a magnetic layer on a non-magnetic support and a method for recording and reproducing the same, and more particularly, to helical scan magnetic recording using a magnetoresistive read head. The present invention relates to a magnetic recording medium suitable for use in a system and a recording / reproducing method thereof.

[0002]

2. Description of the Related Art Conventionally, as a magnetic recording medium, a powder magnetic material such as an oxide magnetic powder or an alloy magnetic powder has been coated on a non-magnetic support by using a vinyl chloride-vinyl acetate copolymer, a polyester resin, a polyurethane resin or the like. So-called coating type magnetic recording media, which are produced by applying and drying a magnetic paint dispersed in an organic binder, are widely used.

On the other hand, as the demand for high-density recording has increased, metal magnetic materials such as Co—Ni, Co—Cr, and Co have been plated or vacuum thin film forming means (vacuum evaporation, sputtering, ion plating, etc.). A magnetic recording medium of the so-called metal magnetic thin film type, which is directly adhered on a non-magnetic support by a method such as the above, has been attracting attention.

The metal magnetic thin film type magnetic recording medium is excellent in coercive force, remanent magnetization, squareness ratio, etc., is excellent in electromagnetic conversion characteristics at short wavelengths, and can extremely reduce the thickness of the magnetic layer. The thickness loss at the time of demagnetization and reproduction is small, and there is no need to mix a binder which is a non-magnetic material in the magnetic layer.Therefore, the packing density of the magnetic material can be increased and a large magnetization can be obtained. Has advantages.

Further, in order to improve the electromagnetic conversion characteristics of this type of magnetic recording medium and to obtain a larger output, when forming the magnetic layer of the magnetic recording medium, the magnetic layer is deposited obliquely. A so-called oblique deposition has been proposed, and has been put to practical use as a magnetic tape for a high-quality VTR and a digital VTR.

[0006]

In the magnetic recording medium as described above, it is desired to improve the recording density. Therefore, it is considered to reduce the interval between adjacent recording tracks, that is, the track pitch. . However, when the track pitch is reduced, the influence on adjacent recording tracks when forming a predetermined recording track becomes a serious problem. In other words, when the track pitch is reduced, a signal already written on an adjacent recording track may be erased due to a change in the recording track width or a bending of the recording track.

[0007] As described above, the magnetic recording medium has a problem in that when an adjacent recording track is affected, the reproduction output by the reproduction head fluctuates greatly.

In view of such circumstances, the present invention has been proposed, and even when the track pitch becomes narrow,
It is an object of the present invention to provide a magnetic recording medium and a recording / reproducing method which exhibit excellent reproduction output, can reliably form a recording track, and can construct an unprecedented high-density recording system.

[0009]

A magnetic recording medium according to the present invention, which has achieved the above-mentioned objects, comprises a magnetic layer formed on a non-magnetic support, and has a residual magnetization Mr and a film thickness t of the magnetic layer. Is 0.5 to 3.0 memu / cm ^2.
Wherein the track pitch of the recording tracks formed on the magnetic layer is 1 to 5 μm.

In the magnetic recording medium according to the present invention configured as described above, the value of Mr.t is set to 0.5 to 3.0 memu.
/ Cm ² ensures that a recording track is formed even when the track pitch is in the range of 1 to 5 μm. In other words, the signal written on the magnetic recording medium has a desired track width.

Further, according to the recording / reproducing method for a magnetic recording medium according to the present invention, which achieves the above-mentioned object, a magnetic layer is formed on a non-magnetic support, and the residual magnetization Mr and the film thickness t of the magnetic layer are formed. Is 0.5 to 3.0 memu / c.
For a magnetic recording medium of m ² ,
A recording track is formed at a track pitch of μm.

In the recording / reproducing method for the magnetic recording medium configured as described above, the value of Mr · t is set to 0.5 to 3.0 mem.
A magnetic head forms a recording track on a magnetic recording medium defined as u / cm ² such that the track pitch is 1 to 5 μm. Therefore, according to this method, 1
It is possible to reliably form a recording track having a range of up to 5 μm.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of a magnetic recording medium and a recording / reproducing method for the same according to the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a magnetic recording medium according to the present invention.
As shown in (1), a magnetic layer 2 formed of a metal magnetic thin film on a non-magnetic support 1 can be exemplified. The magnetic layer 2 is formed by, for example, a thin film forming device such as a vacuum evaporation device or a sputtering device. The thin film forming apparatus forms a magnetic layer 2 by running a long non-magnetic support 1 at a predetermined line speed and depositing a metal magnetic material with a predetermined thickness on the running non-magnetic support. I do.

The magnetic recording medium has a protective layer 3 such as a carbon film formed on the surface of the magnetic layer 2 and a surface of the non-magnetic support 1 opposite to the surface on which the magnetic layer 2 is formed. It has a formed back coat layer 4 and a lubricating layer 5 formed on the protective layer 3. The protective layer 3 is formed so as to cover the magnetic layer 2 so that corrosion, damage, and the like of the magnetic layer 2 can be prevented. Further, the back coat layer 4 and the lubrication layer 5 can improve the running property of the magnetic recording medium formed in a tape shape.

The magnetic layer 2 is formed by sputtering, C
VD (Chemical Vapor Deposit)
ion) method, vacuum evaporation method, ion plating method, etc.
It may be formed using any conventionally known method. Further, the magnetic layer 2 is preferably formed, for example, on a Cr underlayer. As the underlayer, CrTi, CrMo, CrV, or the like is used in addition to Cr.

If the temperature of the nonmagnetic support 1 cannot be increased at the time of film formation, the magnetic layer 2 is preferably a CoPt-based material. Specifically, CoCrPt, CoCrTaP
t, CoPt-SiO ₂ , CoPt-SiO ₂ , CoC
rTaPtNb and the like can be exemplified. The temperature of the nonmagnetic support 1 during film formation is about 20
When the temperature can be raised to 0 ° C. or higher, CoCrTa can be exemplified. Also, CoCrTaPt, CoC
rTaPtNb can also be applied to the case where the temperature of the nonmagnetic support 1 can be raised to about 200 ° C. or more during film formation.

In this magnetic recording medium, the magnetic layer 2
The product Mr · t of the residual magnetization Mr and the film thickness t is 0.5 to
It is regulated to 3.0 memu / cm ² . At this time, the thickness of the magnetic layer 2 can be controlled by changing the line speed in the thin film forming apparatus.
The amount of residual magnetization can be controlled by changing the amount of oxygen introduced during film formation.

In the magnetic recording medium, by controlling these two parameters, the product Mr · t of the residual magnetization amount Mr and the film thickness t of the magnetic layer 2 is 0.5 to 3.0 memu / cm.
Stipulated in ² .

Of course, the configuration of the magnetic recording medium is not limited to the one described above, but may be a laminate of a plurality of magnetic layers. Furthermore, the magnetic recording medium may include a magnetic layer having perpendicular anisotropy or in-plane random orientation. The magnetic recording medium may be of a coating type obtained by applying a magnetic paint obtained by kneading and dispersing a magnetic powder such as a fine-particle metal magnetic powder together with a binder onto a non-magnetic support.

The magnetic recording medium configured as described above
Recording and reproduction of signals are performed by a so-called magnetic recording and reproducing device of a helical scan magnetic recording system. This magnetic recording / reproducing apparatus is a helical scan type magnetic recording / reproducing apparatus that performs recording / reproducing using a rotating drum, and uses an MR head as a reproducing magnetic head mounted on the rotating drum.

FIGS. 2 and 3 show one configuration example of a rotary drum device mounted on the magnetic recording / reproducing apparatus. Note that FIG.
FIG. 3 is a perspective view schematically showing the rotary drum device 6, and FIG. 3 is a plan view schematically showing a magnetic tape feed mechanism 7 including the rotary drum device 6.

As shown in FIG. 2, the rotary drum device 6
A cylindrical fixed drum 8, a cylindrical rotary drum 9, a motor 10 for driving the rotary drum 9 to rotate, a rotary drum 9
A pair of inductive magnetic heads 11 mounted on
a, 11b, and a pair of MR heads 12a, 12b mounted on the rotating drum 9.

The fixed drum 8 is a drum that is held without rotating. On the side of this fixed drum 8,
The lead guide portion 14 extends along the running direction of the magnetic tape 13.
Are formed. As will be described later, the magnetic tape 13 runs along the read guide portion 14 during recording and reproduction. The rotating drum 9 is disposed so that the center axis of the fixed drum 8 coincides with that of the fixed drum 8.

The rotary drum 9 is a drum that is driven to rotate at a predetermined rotation speed by a motor 10 during recording and reproduction on the magnetic tape 13. The rotating drum 9 is formed in a cylindrical shape having substantially the same diameter as the fixed drum 8, and is arranged such that the center axis of the rotating drum 9 coincides with that of the fixed drum 8. And
A pair of inductive magnetic heads 11a and 11b and a pair of MR heads 12a and 12b are mounted on a side of the rotary drum 9 facing the fixed drum 8.

Inductive magnetic heads 11a, 11
b has a sliding surface 15 as shown in FIG. 4, a pair of magnetic cores 16a and 16b are joined via a non-magnetic layer 17, and a magnetic field generating means (such as a coil) is attached to the magnetic cores 16a and 16b. (Not shown)) is a recording magnetic head wound thereon, and is used when recording a signal on the magnetic tape 13. The inductive magnetic heads 16a and 16b form an angle of 180 ° with the center of the rotating drum 9 such that their sliding surfaces 15 protrude from the outer periphery of the rotating drum 9.
It is installed in. Note that these inductive magnetic heads 11a and 11b are set so that the azimuth angles are opposite to each other so that azimuth recording is performed on the magnetic tape 13.

This inductive magnetic head 11a,
11b, the pair of magnetic cores 16a, 16b includes a core member 18 made of a soft magnetic material such as ferrite, and a metal soft magnetic thin film 19 laminated on one main surface of the core member 18, respectively. In addition, in the inductive magnetic heads 11a and 11b, at least one end of the abutting surfaces of the pair of metal soft magnetic thin films 19 that are brought together via the nonmagnetic layer 17 is trimmed.
That is, at least one of the butted ends of the pair of metal soft magnetic thin films 19 is cut so as not to be exposed on the sliding surface 15.

In the inductive magnetic heads 11a and 11b thus configured, a pair of magnetic cores 16a,
By disposing the non-magnetic layer 17 between the pair of magnetic cores 16b, a magnetic gap is formed between the pair of magnetic cores 16a and 16b. Thereby, the inductive magnetic head 1
In 1a and 11b, when a pair of magnetic cores 16a and 16b are magnetized by a magnetic field generating means such as a coil (not shown),
A leakage magnetic field is generated between the pair of metal soft magnetic thin films 19. The inductive magnetic heads 11a and 11b generate a leakage magnetic field in the magnetic gap and apply the leakage magnetic field to the magnetic layer 2 of the magnetic recording medium to record a signal.

For this reason, in the inductive magnetic heads 11a and 11b, the width of the butting surface exposed on the sliding surface 15 is the track width of the recording track formed on the magnetic recording medium.

On the other hand, the MR heads 12a and 12b
As shown in FIG. 1, a reproducing magnetic head having an MR element 20 as a magnetic sensing element for detecting a signal from the magnetic tape 13 is used when reproducing a signal from the magnetic tape 13. These MR heads 12a and 12b are mounted on the rotating drum 9 such that the angle formed between them with respect to the center of the rotating drum 9 is 180 °, and one end face of the MR element projects from the outer periphery of the rotating drum 9. I have. These MR heads 12a and 12b are set so that the azimuth angles are opposite to each other so that signals recorded azimuthally on the magnetic tape 13 can be reproduced.

The MR heads 12a and 12b are made of Ni.
-A pair of magnetic shields 22 made of a soft magnetic material such as Zn polycrystalline ferrite are provided, and the MR element 20 is sandwiched between the pair of magnetic shields 22 via an insulator. Further, the MR heads 12a and 12b are SALs (Soft Adj) which are disposed to face the MR element 20 via an insulator.
acent Layer) film 23. The MR element 20
It is made of a soft magnetic material such as Ni-Fe or the like whose resistance changes according to the magnitude of an external magnetic field due to the anisotropic magnetoresistance effect (AMR). The SAL film 23 is for applying a bias magnetic field to the MR element 20 by a so-called SAL bias method, and is made of a magnetic material having a low coercive force and a high magnetic permeability such as permalloy. The insulator is the MR element 20
To insulate the SAL film 23 from the SAL film 23 and prevent electrical shunt loss, and is made of an insulating material such as Ta.
Although not shown, a pair of terminals are led out from both ends of the MR element 22.
A sense current can be supplied to the element 22.

In the magnetic recording / reproducing apparatus, during recording / reproducing, the magnetic tape 7 is fed from the supply reel 24 via guide rollers 25 and 26 so as to be wound around the rotary drum device 6 as shown in FIG. Recording and reproduction are performed by the rotating drum device 6. The magnetic tape 13 recorded and reproduced by the rotary drum device 6 is guided by guide rollers 27,
28, a capstan 29, and a guide roller 30, and are sent to a take-up roll 31. That is, the magnetic tape 13 is fed at a predetermined tension and speed by a capstan 29 driven to rotate by a capstan motor 32, and is wound on a winding roll 31 via a guide roller 30.

At this time, the rotary drum 9 is driven to rotate by a motor 10 as shown by an arrow A in FIG.
On the other hand, the magnetic tape 13 is sent along the lead guide portion 14 of the fixed drum 8 so as to slide obliquely with respect to the fixed drum 8 and the rotating drum 9. In other words, the magnetic tape 13 is fed along the tape running direction from the tape entrance side along the lead guide portion 14 so as to be in sliding contact with the fixed drum 8 and the rotating drum 9 as shown by the arrow B in FIG. Then, as shown by an arrow C in FIG.

In the magnetic recording / reproducing apparatus, signals are recorded on the magnetic tape 13 running in this manner by a pair of inductive magnetic heads 11a and 11b. At this time, one inductive magnetic head 11a forms a predetermined recording track (hereinafter, referred to as “Ach”) on the magnetic tape 13, and the other magnetic head forms a predetermined recording track (hereinafter, “Ach”) adjacent to Ach. Bch ")
To form That is, a pair of inductive magnetic heads 11a and 11b
Signals are recorded by alternately forming channels. Note that these Ach and Bch have different azimuth angles.

The inductive magnetic head 11a
Forms an Ach so as to overlap a part of the already written Bch in the width direction. Conversely, the inductive magnetic head 11b forms the Bch so as to overlap a part of the already written Ach in the width direction. That is, the inductive magnetic heads 11a and 11b
Forms a new recording track while overwriting a part of the already written recording track in the width direction. Hereinafter, this recording method is referred to as “overwrite recording”.

At this time, the pair of inductive magnetic heads 11a and 11b overwrite at the trimmed end. That is, the pair of inductive magnetic heads 11a and 11b are positioned with respect to the magnetic tape 13 such that the trimmed end and the already written recording track face each other.

The track pitch of the recording tracks thus formed, that is, the distance from the center in the width direction of Ach to the center in the width direction of the adjacent Bch is in the range of 1 to 5 μm. By setting the track pitch to 1 to 5 μm, more recording tracks can be formed, and high-density recording can be performed on the magnetic tape 13.

In the magnetic tape 13, the magnetic layer 2
Is set to 0.5 to 3.0 memu / cm ² , it is possible to reliably form a recording track written at a narrow track pitch of 1 to 5 μm. When signals are recorded in the inductive magnetic heads 11a and 11b, an unexpected leakage magnetic field is generated at both ends of the butted surfaces of the metal soft magnetic thin film 19, and adjacent recording tracks are erased more than necessary. There is a fear. That is, by an unexpected leakage magnetic field generated at both ends of the butted surface of the metal soft magnetic thin film 19,
There is a risk that side erasure may occur, such as erasing the already written recording track more than necessary.

However, since the value of Mr · t of the magnetic layer ² is specified to be 0.5 to 3.0 memu / cm ² ,
An unexpected leakage magnetic field generated at both ends of the butted surface of the metal soft magnetic thin film 19 can be prevented from being written on the magnetic tape 13. That is, this magnetic tape 1
In No. 3, a recording track having a desired width can be surely formed without erasing (side erasing) an already written recording track more than necessary.

In particular, when the track pitch is defined as 1 to 5 μm, the width of the recording track itself becomes 5 μm or less.
As described above, if a recording track is erased more than necessary in the width direction in a narrow recording track of 5 μm or less, signal deterioration becomes remarkable as compared with a case of a wide recording track. In other words, the track pitch is 1-5 μm.
When m is specified, signal degradation due to side erasure becomes particularly remarkable. However, this magnetic tape 13
Then, the value of Mr · t of the magnetic layer 2 is set to 0.5 to 3.0 mem.
Since it is defined as u / cm ² , the signal is not deteriorated even if the track pitch is narrow, and the recording track is formed reliably.

Further, in the pair of inductive magnetic heads 11a and 11b, the trimmed end and the already written recording track face each other, and the recording track is formed while overwriting a predetermined width. At the trimmed end, an unexpected leakage magnetic field is less likely to occur than at the untrimmed end. For this reason, by forming the recording track with the trimmed end and the already written recording track facing each other, it is possible to more reliably prevent the already written recording track from being erased more than necessary. .

The recording tracks thus formed are reproduced by the above-described MR heads 12a and 12b. The MR heads 12a and 12b are mounted on the rotating drum 9, and are read-only magnetic heads that detect signals from the magnetic tape 13 by a helical scan method using a magnetoresistance effect. The MR heads 12a and 12b are suitable for high-density recording because they have higher sensitivity and higher reproduction output than inductive magnetic heads that perform recording and reproduction using electromagnetic induction. Therefore, higher density recording can be achieved by using the MR heads 12a and 12b as the reproducing magnetic heads.

The MR heads 12a,
When reproducing a signal from the magnetic tape 13 using the magnetic tape 12b, the magnetic tape 13 is slid on the MR element 20, and the signal is transmitted through the terminals connected to both ends of the MR element 20.
A sense current is supplied to the R element 20 and a voltage change of the sense current is detected. Specifically, while applying a predetermined voltage from a terminal connected to one end of the MR element 20,
The terminal connected to the other end of the MR element 20 is connected to the rotating drum 9
Connect to. Here, the rotating drum 9 is electrically connected to the fixed drum 8 via a rotating shaft, and the fixed drum 8 is grounded. Therefore, one terminal connected to the MR element 20 is grounded via the rotating shaft of the rotating drum 9 and the fixed drum 8.

When a sense current is supplied to the MR element 20 while the magnetic tape 13 is slid, the M formed on the MR element 20 in response to the magnetic field from the magnetic tape 13.
The resistance value of the R element changes, and as a result, a voltage change occurs in the sense current. Therefore, by detecting the voltage change of the sense current, the signal magnetic field from the magnetic tape 13 is detected, and the signal recorded on the magnetic tape 13 is reproduced.

In the MR heads 12a and 12b to be used, the MR element 20 may be any element exhibiting a magnetoresistance effect. For example, by stacking a plurality of thin films, a larger magnetoresistance effect can be obtained. ,
A so-called giant magnetoresistive element (GMR element) can also be used. The method of applying a bias magnetic field to the MR element may not be the SAL bias method, for example, a permanent magnet bias method, a shunt current bias method, a self-bias method, an exchange bias method, a barber pole method, a split element method, Various methods such as a servo bias method can be applied. The giant magnetoresistance effect and various bias methods are described in detail in, for example, "Magnetoresistance Head-Basic and Application Translated by Kazuhiko Hayashi" issued by Maruzen Co., Ltd.
In order to apply only the magnetic field to be reproduced among the signals from the magnetic tape 13 to the MR element 20, it acts to draw in the magnetic field other than the magnetic field to be reproduced. That is, according to the pair of shields 22, only the magnetic field to be reproduced is applied to the MR element 20.
Can be applied.

In the magnetic tape 13, the value of Mr · t is 0.1.
Since it is defined as ⁵ to 3.0 memu / cm ² , M
Reproduction is surely performed by the R heads 12a and 12b. In other words, Mr · t is 0.5 memu / cm ²
If less than, the magnetic field from the magnetic tape 13 is insufficient,
Reproduction by the MR heads 12a and 12b may become difficult. Also, Mr · t is 3.0 mem.
If it exceeds u / cm ² , the MR element 20 may be saturated, and it may be difficult to obtain an accurate reproduction output without distortion.

[0047]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments to which the present invention is applied will be described in detail based on experimental results.

Example 1 First, a polyethylene terephthalate film was prepared,
On this surface, a Co-based metal magnetic thin film was formed by a vacuum evaporation method. In addition, the polyethylene terephthalate film contains a filler having a predetermined particle size, and forms appropriate protrusions on the surface.

Thereafter, a carbon film was formed on the metal magnetic thin film formed as described above by sputtering or CVD.

Then, on the surface of the non-magnetic support opposite to the surface on which the magnetic layer is formed, a back coat layer made of carbon and urethane resin is formed to a thickness of 0.6 μm, and on the surface of the carbon film. A lubricant made of perfluoropolyether was applied, and then cut into 8 mm width to complete a magnetic tape.

In the magnetic tape manufactured as described above, the value of Mr · t was 2.3 memu / cm ² .

Next, the electromagnetic conversion characteristics of the sample tape were measured. Specifically, a modified version of an 8 mm VTR is used, a signal having a recording wavelength of 0.5 μm is recorded as Ach on a magnetic tape, and a recording wavelength of 0.2 μm is recorded as Bch.
A 7 μm signal was recorded. A helical scan type MR head was used for reproducing the sample tape.

It should be noted that Mr · t is determined using Mr measured by a VSN measuring instrument and the thickness t of the magnetic layer obtained from a cross-sectional photograph by an electron microscope.

Example 2 In Example 2, a magnetic tape was produced in the same manner as in Example 1 except that the recording track width was 1.8 μm, and overwrite recording was performed.

Example 3 In Example 3, the recording was performed at a recording wavelength of 0.
A signal of 7 μm was recorded, and the recording wavelength was 0.5 μm as Bch.
A magnetic tape was produced in the same manner as in Example 1 except that the signal m was recorded.

Example 4 In Example 4, the value of Mr · t was 1.4 memu / cm ^2.
A magnetic tape was prepared in the same manner as in Example 2 except that a magnetic tape was prepared, and overwrite recording was performed.

Fifth Embodiment In a fifth embodiment, the recording is performed at a recording wavelength of 0.
A signal of 7 μm was recorded, and the recording wavelength was 0.5 μm as Bch.
A magnetic tape was prepared in the same manner as in Example 1 except that the signal of m was recorded, and overwrite recording was performed.

Comparative Example 1 In Comparative Example 1, the value of Mr · t was 6.0 memu / cm ^2.
A magnetic tape was prepared in the same manner as in Example 1 except that a magnetic tape was prepared, and overwrite recording was performed.

COMPARATIVE EXAMPLE 2 In Comparative Example 2, recording was performed on a magnetic tape with Ach as a recording wavelength of 0.
A signal of 7 μm was recorded, and the recording wavelength was 0.5 μm as Bch.
A magnetic tape was produced in the same manner as in Comparative Example 1 except that the signal of m was recorded.

Comparative Example 3 In Comparative Example 3, the value of Mr · t was 3.5 memu / cm ^2.
A magnetic tape was prepared in the same manner as in Example 1 except that a magnetic tape was prepared, and overwrite recording was performed.

COMPARATIVE EXAMPLE 4 In Comparative Example 4, a magnetic tape was recorded on a magnetic tape with an Ach and a recording wavelength of 0.
A signal of 7 μm was recorded, and the recording wavelength was 0.5 μm as Bch.
A magnetic tape was produced in the same manner as in Comparative Example 3 except that the signal of m was recorded.

Comparative Example 5 In Comparative Example 5, the value of Mr · t was 7.2 memu / cm ^2.
A magnetic tape was prepared in the same manner as in Example 1 except that a magnetic tape was prepared, and overwrite recording was performed.

COMPARATIVE EXAMPLE 6 In Comparative Example 6, a magnetic tape was recorded as Ach with a recording wavelength of 0.
A signal of 7 μm was recorded, and the recording wavelength was 0.5 μm as Bch.
A magnetic tape was produced in the same manner as in Comparative Example 5 except that the signal of m was recorded.

Examples 1 to 5 and Comparative Example 1
From Comparative Example 6, the recording track width and the side erase amount were measured. At this time, the recording track width and the side erase amount were obtained from a magnetization pattern observed with a magnetic force microscope. Table 1 shows the results.

[0065]

[Table 1]

As can be seen from Table 1, when comparing the first and second embodiments with the third embodiment, and comparing the fourth and fifth embodiments, the recording wavelengths of the signals to be recorded on Ach and Bch are as follows. Even if they differ, the recording track width and the side erase amount are substantially constant. From this fact, it has become clear that a narrow recording track can be reliably formed by defining the value of Mr · t to be 0.5 to 3.0 memu / cm ² .

On the other hand, Comparative Examples 1 and 2
Compared with Comparative Examples 3 and 4, and Comparative Examples 5 and 6, since the value of Mr · t is larger than 3.0 memu / cm ² , the recording wavelengths of the signals recorded on Ach and Bch are different. It can be seen that the recording track width and the side erase amount change. The value of Mr · t is 0.5me
If it is smaller than mu / cm ^2, the output of the helical scan type MR head is not sufficient, and it is difficult to perform reproduction.

On the other hand, in Examples 1 to 5 described above, when performing overwrite recording, a magnetic head in which the end of the magnetic gap on the overwriting side was trimmed was used. On the other hand, when overwrite recording was performed using a magnetic head in which the end of the magnetic gap was not trimmed, the side erase amount was 2.1 μm. Therefore, when performing overwrite recording, it is preferable to use a magnetic head in which the end of the magnetic gap on the overwrite side is trimmed.

The above description relates to the definition of Mr · t. Hereinafter, the reason for setting the recording track width to 1 to 5 μm will be examined.

Example 6 In Example 6, the value of Mr · t was 2.3 memu / cm ^2.
A magnetic tape was produced in the same manner as in Example 1, and overwrite recording was performed with a recording track width of 2.0 μm.

Embodiment 7 In Embodiment 7, the value of Mr · t is 2.3 memu / cm ^2.
A magnetic tape was produced in the same manner as in Example 1, and overwrite recording was performed with a recording track width of 5.0 μm.

Comparative Example 7 In Comparative Example 7, the value of Mr · t was 2.3 memu / cm ^2.
A magnetic tape was produced in the same manner as in Example 1, and overwrite recording was performed with a recording track width of 7.0 μm.

Comparative Example 8 In Comparative Example 8, the value of Mr · t was 6.0 memu / cm ^2.
A magnetic tape was produced in the same manner as in Example 1 except that the recording track width was 2.0 μm.

Comparative Example 9 In Comparative Example 9, the value of Mr · t was 6.0 memu / cm ^2.
A magnetic tape was manufactured in the same manner as in Example 1 except that the recording track width was changed to 5.0 μm, and overwrite recording was performed.

Comparative Example 10 In Comparative Example 10, the value of Mr · t was 6.0 memu / cm.
^A magnetic tape was produced in the same manner as in Example 1 except that the recording track width was changed to 2, and overwrite recording was performed with a recording track width of 7.0 μm.

With respect to Examples 6 and 7 and Comparative Examples 7 to 10 manufactured as described above, Ach and B
ch recording wavelengths of 0.5 μm and 0.7 μm, respectively.
Alternatively, the fluctuation width of the recording track and the fluctuation width of the reproduction output at 0.7 μm and 0.5 μm, respectively, were measured.
Table 2 shows the results.

[0077]

[Table 2]

As can be seen from Table 2, in Comparative Examples 7 and 10, the width of the recording track is set to 7.0 μm, so that the output fluctuation is small regardless of the value of Mr · t. However, when the width of the recording track is larger than 5.0 μm, the recording density cannot be improved.

When Examples 7 and 8 are compared with Comparative Examples 8 and 9, the recording track is set to 5.0 μm or less in order to improve the recording density. In Comparative Examples 8 and 9, The value of Mr · t is 3.0 memu / cm ²
Since the width is larger, the fluctuation width of the recording track and the fluctuation width of the reproduction output are larger. In contrast, Example 7
In the eighth embodiment, while the recording track is set to 5.0 μm or less to improve the recording density, the fluctuation width of the recording track and the reproduction output are also small. Therefore,
The track pitch is set to 1.
When the value is 0 to 5.0 μm, the value of Mr · t is 3.0 me.
By controlling the magnetic tape to not more than mu / cm ² ,
It is possible to reliably form a recording track while supporting high-density recording.

[0080]

As is clear from the above description, in the magnetic recording medium according to the present invention, since the value of the product Mr · t of the residual magnetization Mr and the film thickness t is defined, 1 to 5 μm
Such a narrow track pitch can be surely formed.

Further, according to the recording / reproducing method according to the present invention, the use of a magnetic recording medium in which the value of the product Mr · t of the residual magnetization amount Mr and the film thickness t is set to a predetermined value is unprecedented. It is possible to construct a high-density recording system.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a magnetic recording medium.

FIG. 2 shows a configuration example of a rotary drum device mounted on a magnetic recording / reproducing device of a helical scan magnetic recording system.
It is a perspective view showing the outline.

FIG. 3 is a plan view schematically showing a configuration example of a magnetic tape feeding mechanism including the rotary drum device.

FIG. 4 is a plan view of a sliding surface of a magnetic head that performs recording.

FIG. 5 is a perspective view schematically showing a configuration of a magnetoresistive magnetic head for performing reproduction.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 nonmagnetic support, 2 magnetic layer, 3 protective layer, 4 backcoat layer, 5 lubricating layer, 11 inductive magnetic head, 12 MR head, 13 magnetic tape

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shinichi Fukuda 6-35, Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (72) Inventor Tadashi Osue 6-35, Kita-Shinagawa, Shinagawa-ku, Tokyo Sony Corporation F term (reference) 5D006 BB07 DA00 FA09 5D091 AA03 CC01 CC21 DD03 EE01

Claims (6)

[Claims] 1. A magnetic recording medium in which a magnetic layer is formed on a non-magnetic support, wherein the product Mr · t of the residual magnetization amount Mr and the film thickness t of the magnetic layer is 0.5 to 3.0 memu. / Cm ² , and the track pitch of recording tracks formed on the magnetic layer is 1 to 5 μm. 2. The magnetic recording medium according to claim 1, wherein said magnetic layer is made of a metal magnetic thin film. 3. A magnetic layer is formed on a nonmagnetic support, and a product Mr · t of a residual magnetization amount Mr and a film thickness t of the magnetic layer.
A recording / reproducing method, wherein a magnetic head forms recording tracks at a track pitch of 1 to 5 μm on a magnetic recording medium having a value of 0.5 to 3.0 memu / cm ² . 4. The magnetic head according to claim 1, wherein at least one end of a pair of magnetic cores joined via a non-magnetic material is trimmed in a direction substantially parallel to a sliding direction of the magnetic recording medium. 4. The recording / reproducing method according to claim 3, wherein: 5. The recording / reproducing method according to claim 3, wherein the magnetic recording medium is reproduced by a magneto-resistance effect type magnetic head mounted on a rotary drum device for performing helical scanning. 6. The recording / reproducing method according to claim 4, wherein the magnetic head forms a recording track while overwriting the trimmed end.