JP2001143202A - Magnetic recording method with narrow track - Google Patents

Abstract

PROBLEM TO BE SOLVED: To permit the recording with the track width narrower than the core width of a write head constituting a composite thin film magnetic head, as to the magnetic recording method with the narrow track. SOLUTION: The narrow track 1 is formed by erasing a part in the width direction of the track wherein the information is written, and the information is recorded by repeating this writing procedure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a narrow track magnetic recording method, and more particularly to a narrow track magnetic recording method characterized by a procedure for recording with a track width narrower than a write head core width.

[0002]

2. Description of the Related Art With the increase in recording density of a magnetic recording device such as a hard disk device in recent years, the interval between recording bits has become narrower. It is important not only to improve the performance of the head but also to increase the coercive force and reduce noise of the magnetic recording medium itself.

Also, the radial density of the disk substrate, that is, the track density, has been increasing along with the decrease in the core width of the write head. Thus, in order to improve the areal recording density, the recording bit density has to be increased. There are approaches for reducing the interval, that is, the bit pitch, and approaches for reducing the track interval, that is, the track pitch.

[0004] One of the approaches for narrowing the bit pitch is to shorten the gap length of the thin-film magnetic head for writing. On the other hand, one approach for narrowing the track pitch is for writing. This is to reduce the core width of the thin film magnetic head. Various techniques for narrowing the track have been proposed, but are based on hardware changes due to technical development.

[0005] The present portable recording medium is a DVD-ROM.
5 Gbit / in ² ($ 775 Mbit / c
m ² ) are commercially available, but it is expected that the storage capacity required for portable recording media, that is, portable disks, will further increase in the future.

Here, the state of a track on a conventional magnetic recording medium will be described with reference to FIG. FIG. 9A is a diagram schematically showing an example of a track written on a magnetic recording medium, and is composed of a row of recording bits written with a core width of a write head of 1 μm. The width T of the track 31 is about 1 μm, and the space width S = 0.
A plurality of tracks 31 are arranged over 35 μm. Since the pitch P in this case is 1.35 μm, the recording density in the radial direction, that is, TPI (Truck Per
Inch) is about 18.8 kTPI [≒ 2.54 cm /
1.35 μm (≒ 7.4 k tracks / cm)].

FIG. 9 (b) is a diagram schematically showing the state of the recorded recording bit 33.
3 may be formed at both ends, but the read head core width 32 is smaller than the write head core width, for example, 0.5 μm. No error will occur.

[0008]

However, when the storage capacity is required to be several tens Gbit / in ² (≒ several Gbit / cm ² ) or more, it is difficult to cope with the problem by reducing the core width of the conventional write head. There is a problem that it is difficult. That is, in general, the track density is about 10 to 30 times lower than the linear density, and it is necessary to manufacture a thinner ride head to reduce the core width. However, there is a limit to head processing by ion milling or the like. , The wall of narrow track.

Accordingly, it is an object of the present invention to perform recording with a track width narrower than a core width of a write head constituting a composite type thin film magnetic head.

[0010]

Here, means for solving the problems in the present invention will be described with reference to FIG. See FIG. 1. (1) The present invention relates to a narrow head in a magnetic recording / reproducing apparatus including a reproducing head for magnetically reproducing information, a write head for magnetically recording information, and a magnetic recording medium for writing information. The magnetic recording method is characterized in that a narrow track 1 is formed by erasing a part of the track on which information is written in the width direction, and this writing procedure is repeated.

As described above, the narrow track 1 is formed by erasing a part of the track on which information is written in the width direction, and by repeating this writing procedure, all the tracks in the magnetic recording medium are changed to the narrow track 1. And thereby the recording density can be arbitrarily improved.

For example, if the write width by the write head is W
By using the same write head to erase a part of the track on which information is written, a narrow track 1 having a width T is formed, and this narrow track procedure is repeated with a space S in between. Accordingly, the recording density can be increased to the maximum (W + S) / (T + S) times the recording density corresponding to the writing limit of the write head itself.

Here, W = 1 μm, S = 0.35 μm,
When T = 0.65 μm, (W + S) / (T + S) = (1 + 0.35) / (0.6
5 + 0.35) = 1.35, so that the recording density can be improved by a factor of 1.35. The width T of the narrow track 1 can be arbitrarily changed depending on the erase width, but cannot be made smaller than the read head core width 2.

Further, by arbitrarily changing the width S of the space, the recording density can be set to an arbitrary recording density within the range of the maximum recording density according to the purpose of use.
In this case, it is necessary to set the tracking characteristics of the write head to be variable in advance.

(2) According to the present invention, in the above (1), when at least one of the outermost diameter and the innermost diameter of the magnetic recording medium is provided with an empty area of at least two tracks and overwritten, It is characterized in that the information to be overwritten is overwritten in a state where it is previously saved in a free area.

In this manner, by providing at least one of the outermost diameter or the innermost diameter of the magnetic recording medium with an empty area of at least two tracks, it is possible to overwrite even when recording is performed by the narrow track 1. . That is, when information is recorded on the narrow track 1, when overwriting, in the erasing step accompanying the formation of the narrow track 1, the information written on the next track is also erased. That is, although the written information cannot be corrected, the written information can be corrected by providing an empty area and overwriting the information to be overwritten in a state where the information to be overwritten is sequentially saved in the empty area in advance.

(3) According to the present invention, in the above (1), a random access memory is provided in the magnetic recording / reproducing apparatus, and when overwriting, information to be overwritten is stored in the random access memory in advance. It is characterized in that it is overwritten in a state where it is evacuated.

As described above, when correcting written information, there is no need to provide an empty area on the magnetic recording medium.
DRAM (Dynamic
Random access memory), SRAM (static random access memory), or FeRA
A random access memory such as M (ferromagnetic RAM) may be used, and the entire magnetic recording medium can be used as an information recording area, thereby increasing the information recording amount.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Here, a first embodiment of the present invention will be described with reference to FIG. Each drawing is a schematic explanatory view of a step of forming a narrow track in a magnetic disk. Referring to FIG. 2A, first, using a write head having a core width of 1.0 μm, information is written with a track width W ≒ 1.0 μm, and then the same write is performed so as to overlap with the written wide track 13 by 0.35 μm. Using a head, width E ≒ D over 0.95 μm
C erase is performed to erase 0.35 μm of the lower end of the written information in the track width direction, and the track width T =
A narrow track 11 of 0.65 μm is formed. In this case, the width T of the narrow track 11 needs to be larger than the read head core width 12, and here, since the read head core width 12 is 0.5 μm, T = 0.6
Set to 5 μm.

Next, with reference to FIG. 2B, a space S between tracks is made 0.35 μm, and information is written again with a track width W ≒ 1.0 μm using a write head having a core width of 1.0 μm. , The next wide track 13 is formed.

Next, referring to FIG. 2C, the width E is approximately 0.95 μm again using the same write head so as to overlap the written track by 0.35 μm.
Then, DC erase is performed over m to erase 0.35 μm of the lower end of the written information in the track width direction to form a new narrow track 11 having a track width T = 0.65 μm.

Referring to FIG. 2D, by repeating such a procedure, the narrow track 11 is obtained.
Thus, a magnetic disk on which all information is written is completed. In this case, as for the recording density, the track pitch becomes T + S = 0.65 μm + 0.35 μm = 1.0 μm.
35 times improvement. That is, the recording density is 25.4.
kTPI (≒ 10k tracks / cm).

It should be noted that a magnetic disk having CoCrPtTaNb as a magnetic layer is actually set to “0”,
After writing a repetitive pattern of “1” and then performing DC erase with the track width partially overlapping, the MFM
(Magnetic Force Microscope
Observing the MFM image of the surface of the magnetic disk using e), an image of recording bits regularly arranged with a track width of about 0.3 μm was observed as a black and white repetitive pattern, and the track before DC erase was performed. Width is about 1.0μm
It was confirmed that the track could be significantly narrowed as compared with the MFM image of FIG.

When the track width is set to 0.3 μm,
In this case, the read head core width 12 is set to 0.3 μm or less.
However, in the near future, lead
When the core width 12 becomes 0.3 μm or less,
Recording density is 10Gbit / in ^Two(≒ 1.55 Gbit /
cm^Two), A portable magnetic recording medium that exceeds
You.

For example, 10 Gbit / in ² (≒ 1.5
The recording density of 5 Gbit / cm ² ) is the highest in the existing portable recording media, such as DVD-RAM and D-RAM.
The recording density is more than twice that of VD-ROM, etc.
In addition, the information playback speed depends on the hardware
And so on, so that the DVD market can be replaced.

When information is recorded on the entire surface of the magnetic disk by such a writing method, when information in a predetermined area is to be rewritten by overwriting, the nth narrow track of width T is overwritten. When a track having a width W is formed, the information of the (n + 1) th narrow track located next may be destroyed, and a DC erase step for narrowing the track having a width W to a width T so,
Since information on the (n + 1) th narrow track is completely erased, rewriting cannot be performed on the (n + 1) th track and thereafter. However, there is no problem at all in the case of a backup-only disk or a disk for recording moving images or application software, since rewriting is not required.

In the first embodiment of the present invention, the width T of the narrow track 11 is set to 0.65 by setting the interval S between the narrow tracks 11 to 0.35 or more. The recording density can be set arbitrarily within the range of the maximum recording density when S = 0.35 μm.

Next, with reference to FIG. 3, description will be given of a case where writing blur occurs in the first embodiment of the present invention. See FIG. 3A. FIG. 3A is a diagram schematically showing a state of a narrow track when writing blur occurs, and also when writing blur occurs as shown in FIG. Since the write bleed portion at the lower end of the recording bit 14 is erased in the DC erase step, the write bleed portion 15 exists only at the upper end of the recording bit 14.

3B. In this case, the core width of the read head may be set to a narrow read head core width 16 such that noise caused by the writing blur 15 does not cause a problem. That is, in general, it is easier to narrow the core width of the read head than the core width of the write head. Therefore, even when the core width of the write head does not become narrow, a narrow track is formed by the above-described writing method. Information may be read by a read head capable of narrowing the core width.

Next, a second embodiment of the present invention relating to an overwriting method when a narrow track is used will be described with reference to FIGS. FIG. 4 is a flowchart of an overwriting process according to the second embodiment of the present invention. When overwriting m tracks from the n-th track to the m-th track, first, Is checked to see if the free space is continuous for 2 × m tracks or more, and if there is a free space, it is recorded in a free area. In the second embodiment of the present invention, the free area is set for three tracks from the outermost diameter of the magnetic disk.
Since the free space is not continuous for 2 × m tracks or more, the process proceeds to the next step.

Referring to FIGS. 4 and 5A, in the next step, track n, track n + 1,
Also, before the information of the track m is overwritten and erased, the information is read and recorded in the empty area 21 in advance, that is,
Evacuate. It is assumed that the track on which information in the information recording area 22 has already been written is the wide track 13 corresponding to the core width of the write head. In this case, the track width in the free area 21 is The wide track 13 corresponding to the core width of the head may be used.

Referring to FIGS. 4 and 5 (b), in the next step, the track n 'is obtained by overwriting the track n with the corrected information of the track n.
In this case, since the track n 'is in a state of being written, the track n' remains the wide track 13 corresponding to the core width of the write head.

Next, referring to FIGS. 4 and 6 (c), the track n 'composed of the wide track 13 is subjected to DC erase using the write head so as to partially overlap the track n' in the track width direction. In this case, the track n ″ is composed of the narrow track 11. In this case, for example, a part of the track n + 1 overlaps the DC erase area 17 and the information is erased, but the information of the track n + 1 is already saved in the empty area 21. There is no problem.

Referring to FIGS. 4 and 6 (d), in the next step, the information of track m + 1 is read out and saved in the portion of track n in the empty area 21 where overwriting has already been completed. By reading the information and repeating the procedure similar to the overwriting procedure for the track n, that is, the write-DC erase, the track n + 1 composed of the wide track 13 is replaced with the track n ′ + composed of the wide track 13.
The track m is converted into a narrow track n ″ +1 via the track 1, and then the track m including the wide track 13 is converted into a narrow track m ″ via the track m ′ including the wide track 13.

In the steps so far, as shown in FIG. 6D, the next track m
An empty space 18 corresponding to approximately one track is formed between +1 and +1. However, this empty space becomes a useless area as it is, and the useless space increases as the number of overwrites increases.

Then, the number of overwrites X is counted, and it is determined whether or not the number of times X exceeds the number of times Y not showing the superiority of the recording method of the present invention. The overwrite operation ends. On the other hand, when the number of overwrites X exceeds Y, in order to reduce waste in the magnetic disk space, a recording refilling operation described later with reference to FIGS. 7 and 8 is performed.

The number of times Y depends on the wide track width before rewriting, the narrow track width after rewriting, the width of the space between tracks, and the width of the DC erase area.

As described above, according to the second embodiment of the present invention, since a continuous empty area is provided in the magnetic disk, the disadvantage of the overwriting which is a disadvantage of the narrow track magnetic recording method, which cannot be performed, is solved. be able to.

In the above description, all tracks before rewriting are wide tracks. However, the present invention is also applied to narrow tracks. In this case, the next track is always written along with rewriting. Since the information is erased, all tracks after the track to be rewritten must be overwritten even when there is no correction, but this is the same as the recording repacking operation described later.

Next, with reference to FIGS. 7 and 8, a description will be given of the recording and re-packing operation according to the second embodiment of the present invention. I do. FIG. 7 is a flowchart of a record refilling operation according to the second embodiment of the present invention.
FIG. 8 is a schematic explanatory view of a process of forming a narrow track in a magnetic disk. Referring to FIGS. 7 and 8 (a), first, information of track 1, track 2, and track 3 is read and recorded in the free area 21 in advance. In addition,
The track on which information in the information recording area 22 has already been written is assumed to be the wide track 13 corresponding to the core width of the write head.
The width of the track may be the wide track 13 corresponding to the core width of the write head.

Next, by performing DC erasing using a write head so as to partially overlap the track 1 in the track width direction, the track 1 composed of the wide track 13 becomes a narrow track 1 ″ composed of the narrow track 11. In this case, for example, although a part of the track 2 overlaps with the DC erase area 17 and information is erased,
Is already saved in the empty area 21 and there is no problem.

Referring to FIGS. 7 and 8B, in the next step, the track 2
Is written as a track 2 '(not shown) composed of a wide track 13 after the narrow track 1 ", and then a DC erase is performed to form a narrow track 2" composed of a narrow track 11. I do. In this case as well, although a part of the track 3 overlaps the DC erase area 17 and the information is erased, there is no problem since the information of the track 3 is already saved in the empty area 21.

By retreating the empty area 21 and performing the write-DC erase operation up to the last track, the recording re-packing operation is completed. By performing such a recording repacking operation, when a wasteful space is generated due to the overwriting, the waste can be eliminated, and thereby the entire magnetic disk space can be effectively used.

Although the embodiments of the present invention have been described above, the present invention is not limited to the configurations and conditions described in the embodiments, and various changes can be made. For example, in the first embodiment of the present invention, the write width W,
The narrow track width T, the inter-track space S, and the erase width E are merely examples, and may be changed as appropriate depending on the usage pattern or as the write head and read head are miniaturized.

In the second embodiment, when performing overwriting or re-recording, the information of the track to be rewritten and the information of the next track are stored in the free space previously provided at the outermost diameter of the magnetic disk. Although it is provided in the area,
It may be provided at the innermost diameter of the magnetic disk, or may be provided at both.

In the second embodiment, the empty area is set to three tracks. However, it is sufficient that at least two tracks are provided. For example, in the case of two tracks, the track n is overwritten. Then, it is necessary to immediately rewrite track n in the empty area to track m, and then overwrite track n + 1.

Further, the area for saving information due to overwriting is not limited to an empty area provided on a magnetic disk.
AM (dynamic random access memory),
RA such as SRAM (static random access memory) or FeRAM (ferroelectric RAM)
M may be provided to save information in the RAM.

Further, such RAM information is not limited to the inside of the magnetic disk device, but is stored in a RAM of an information processing device to which the magnetic disk device is attached, for example, a personal computer or the like. Is also good.

[0049]

According to the present invention, a track is formed by repeatedly performing writing and partial DC erase using the same write head, so that a narrow track having a track width narrower than the core width of the write head can be obtained. Can be formed,
As a result, the maximum storage capacity can be dramatically increased, which greatly contributes to the increase in the recording density of a magnetic recording / reproducing device such as an HDD. Realization of various applications becomes possible.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a basic configuration of the present invention.

FIG. 2 is an explanatory diagram of the first embodiment of the present invention.

FIG. 3 is an explanatory diagram of a narrow track when writing blur occurs.

FIG. 4 is a flowchart of an overwrite process according to a second embodiment of the present invention.

FIG. 5 is an explanatory diagram of a part of a track state in each flow according to a second embodiment of the present invention.

FIG. 6 is an explanatory diagram of a track state in each flow according to the second embodiment of the present invention from FIG. 5 onward.

FIG. 7 is a flowchart of a record refilling operation according to the second embodiment of the present invention.

FIG. 8 is an explanatory diagram of a state of a track in a recording refilling operation according to the second embodiment of this invention.

FIG. 9 is an explanatory diagram of a track state in a conventional magnetic recording medium.

[Explanation of symbols]

 Reference Signs List 1 narrow track 2 read head core width 11 narrow track 12 read head core width 13 wide track 14 recording bit 15 writing blur 16 narrow read head core width 17 DC erase area 18 free space 21 free area 22 information recording area 31 track 32 read Head core width 33 recording bit 34 writing blur

Claims (3)

[Claims] A reproducing head for magnetically reproducing information;
In a narrow track magnetic recording method in a magnetic recording / reproducing apparatus having a write head for magnetically recording information and a magnetic recording medium for writing information, by erasing a part of a track on which information is written in a width direction. A narrow track magnetic recording method comprising forming a narrow track and repeating this writing procedure. 2. An empty area of at least two tracks is provided in at least one of an outermost diameter and an innermost diameter of the magnetic recording medium, and when overwriting, information to be overwritten is saved in the empty area in advance. 2. The narrow-track magnetic recording method according to claim 1, wherein the overwriting is performed in a state in which the magnetic recording is performed. 3. A magnetic recording / reproducing apparatus, comprising:
2. The narrow track magnetic recording method according to claim 1, wherein an access memory is provided, and when overwriting, the information to be overwritten is overwritten in a state where the information is previously saved in the random access memory.