JP3876402B2 - Narrow track magnetic recording method - Google Patents

Description

[0001]
BACKGROUND 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]
[Prior art]
As the recording density of magnetic recording devices such as hard disk devices has increased in recent years, the interval between recording bits has become narrower, and in order to form smaller recording bits on a magnetic recording medium, the performance of the recording head has been improved. Needless to say, it is important to increase the coercive force and noise of the magnetic recording medium itself.
[0003]
In addition, the radial density of the disk substrate, that is, the track density has also increased with a decrease in the core width of the write head. Thus, in order to improve the surface recording density, the recording bit interval, that is, There are an approach for narrowing the bit pitch and an approach for narrowing the track interval, that is, the track pitch.
[0004]
Of these, one approach to narrow the bit pitch is to shorten the gap length of the write thin film magnetic head, while one approach to narrow the track pitch is to write the thin film magnetic head. It is to narrow the core width.
Various techniques for narrowing the track have been proposed, but this is due to hardware changes due to technical development.
[0005]
The current portable recording medium is about 5 Gbit / in ² (≈775 Mbit / cm ² ) such as a DVD-ROM, but in the future, a portable recording medium, that is, a portable recording medium will be used. The storage capacity required for the disk is expected to increase further.
[0006]
Here, with reference to FIG. 9, the state of the track in the conventional magnetic recording medium will be described.
Reference to FIG. 9A FIG. 9A is a diagram schematically showing an example of a track written on a magnetic recording medium, and consists of a sequence of recording bits written with a core width of a 1 μm write head. The width T of the track 31 is about 1 μm, and a plurality of tracks 31 are arranged via the space width S = 0.35 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 track / cm). )].
[0007]
Reference to FIG. 9B FIG. 9B is a diagram schematically showing the state of the written recording bit 33, and there are cases where the writing bleeding part 34 is formed at both ends of the recording bit 33 due to writing bleeding. However, since the read head core width 32 is narrower than the core width of the write head, for example, 0.5 μm, a read error does not occur when the central portion of the recording bit 33 is read.
[0008]
[Problems to be solved by the invention]
However, when a storage capacity of several tens Gbit / in ² (≈several Gbit / cm ² ) or more is required, it is difficult to cope with the narrow core width of the conventional write head.
In other words, the track density is generally about 10 to 30 times lower than the linear density, and it is necessary to produce a thinner ride head to reduce the core width, but there is a limit to head processing by ion milling or the like. It has become a wall of narrow track.
[0009]
Accordingly, it is an object of the present invention to perform recording with a track width narrower than the core width of the write head constituting the composite thin film magnetic head.
[0010]
[Means for Solving the Problems]
Here, means for solving the problems in the present invention will be described with reference to FIG.
Refer to FIG. 1. (1) The present invention is a narrow track 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. In the magnetic recording method, at least one of the outermost diameter and the innermost diameter of the magnetic recording medium has an empty area of at least two tracks, and a part of the track in which the information is written is completely erased. As a result, the narrow track 1 is formed, and the writing procedure for writing the next information through the space S in which the information is completely erased is repeated, and the m tracks m are overwritten from the nth track n to the mth track. If, checks whether free space of the magnetic recording medium are continuously 2 × m or more tracks, there are 2 × m free space contiguous or track In this case, the free space is overwritten by the narrow track forming method, and when there is no free space of 2 × m tracks or more, at least the information of track n and track n + 1 is read and saved in the free area. The track n ′ is written on the track n, and a part of the track n ′ in which the information is written is completely erased to form a narrow track n ″ and a space in which the information is completely erased is formed. Then, by sequentially repeating the procedure of writing the next information as the track n ′ + 1 until the formation of the narrow track m ″ for the m-th track m, the information to be overwritten is saved in an empty area in advance. It is characterized by overwriting the track of the information to be overwritten in the recorded state.
[0011]
In this way, the narrow track 1 is formed by completely erasing a part of the track in which the information is written in the width direction, and the writing procedure for writing the next information through the space S where the information is completely erased is repeated. As a result, all the tracks in the magnetic recording medium can be made narrow tracks 1, thereby making it possible to arbitrarily improve the recording density.
[0012]
For example, when the write width by the write head is W, a narrow track 1 having a width T is formed by completely erasing a part of a track on which information is written using the same write head, and a space S having a width S is sandwiched. By repeating this procedure for narrowing the track, the recording density can be increased up to (W + S) / (T + S) times the recording density corresponding to the writing limit of the write head itself.
[0013]
Here, when W = 1 μm, S = 0.35 μm, and T = 0.65 μm,
(W + S) / (T + S) = (1 + 0.35) / (0.65 + 0.35)
= 1.35
Therefore, the recording density can be improved by 1.35 times.
The width T of the narrow track 1 can be arbitrarily changed according to the erase width, but cannot be made smaller than the read head core width 2.
[0014]
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.
[0016]
In particular , 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, overwriting is possible even when recording is performed with the narrow track 1.
That is, when information is recorded on the narrow track 1, when overwriting, the information written on the next track is also erased in the erasing process accompanying the formation of the narrow track 1, so the overwriting using the written information is performed. 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.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Here, a reference example which is a premise of the present invention will be described with reference to FIG.
Each figure is a schematic explanatory view of a narrow track forming process in the magnetic disk. 2A. First, using a write head having a core width of 1.0 .mu.m, after writing information with a track width W.apprxeq.1.0 .mu.m, the same write is performed so that it overlaps the written wide track 13 by 0.35 .mu.m. Using the head, DC erase is performed over a width E≈0.95 μm to erase 0.35 μm of the lower end of the written information in the track width direction, and a narrow track 11 having a track width T = 0.65 μm is erased. Form.
In this case, the width T of the narrow track 11 needs to be larger than the read head core width 12. Here, since the read head core width 12 is 0.5 μm, T = 0.65 μm is set. .
[0020]
Next, with reference to FIG. 2B, the space S between the tracks is opened by 0.35 μm, and information is written with a track width W≈1.0 μm again using a write head having a core width of 1.0 μm. A wide track 13 is formed.
[0021]
Next, referring to FIG. 2C, again, DC erase is performed over the width E≈0.95 μm using the same write head so that it overlaps the written track by 0.35 μm, and the track width in the written information is The lower end in the direction of 0.35 μm is erased, and a new narrow track 11 having a track width T = 0.65 μm is formed.
[0022]
See FIG. 2D. By repeating such a procedure, a magnetic disk having all information written by the narrow track 11 is completed.
In this case, the recording density is the track pitch,
T + S = 0.65 μm + 0.35 μm = 1.0 μm
Therefore, it is improved 1.35 times compared to the conventional 1.35 μm.
That is, the recording density is 25.4 kTPI (≈10 ktrack / cm).
[0023]
Note that a repetitive pattern of “0” and “1” is actually written on a magnetic disk having CoCrPtTaNb as a magnetic layer by a write head, and then DC erase is performed by partially overlapping the track width, and then MFM (Magnetic Force). When the MFM image on the surface of the magnetic disk was observed using Microscope), the image of the 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 Compared to an MFM image having a width of about 1.0 μm, it was confirmed that a significantly narrower track was possible.
[0024]
When the track width is 0.3 μm, the read head core width 12 needs to be 0.3 μm or less. However, in the near future, the read head core width 12 will be 0.3 μm or less in a practical machine. In this case, a portable magnetic recording medium having a recording density exceeding 10 Gbit / in ² (≈1.55 Gbit / cm ² ) can be realized.
[0025]
For example, the recording density of 10 Gbit / in ² (≈1.55 Gbit / cm ² ) is more than double the recording density of DVD-RAM, DVD-ROM, etc., which have the highest recording density among existing portable recording media. Since the density and the information reproduction speed are much higher than those of a DVD or the like due to a difference in hardware mechanism, the DVD market can be replaced.
[0026]
When information is recorded on the entire surface of the magnetic disk by such a writing method, when the information in a predetermined area is to be rewritten by overwriting, the nth narrow track having the width T is overwritten by the width W. When forming a track of (n + 1), there is a possibility that the information of the n + 1th narrow track positioned next is destroyed, and in the DC erase process when narrowing the track of width W to width T, n + 1 Since the information of the nth narrow track is completely erased, it is impossible to rewrite the n + 1th and subsequent tracks.
However, in the case of a backup dedicated disk or a disk for recording moving images and application software, no rewriting is required, so there is no problem at all.
[0027]
In the reference example which is the premise of the present invention, the recording density is set in a state where 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. It can be arbitrarily set within the range of the maximum recording density when S = 0.35 μm.
[0028]
Next, with reference to FIG. 3, a case where there is a writing blur in a reference example which is a premise of the present invention will be described.
See FIG. 3A. FIG. 3A is a diagram schematically showing the state of a narrow track when there is a writing blur, and also when a writing blur occurs as shown in FIG. 9B. In the DC erase process, the writing blur portion at the lower end of the recording bit 14 is erased, so that the writing blur portion 15 exists only at the upper end of the recording bit 14.
[0029]
In this case, the core width of the read head may be set to a narrow read head core width 16 that does not cause noise due to the writing bleeding portion 15.
That is, in general, it is easier to narrow the read head core width than the write head core width. Therefore, even when the write head core width is not reduced, 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.
[0030]
Based on the above, a first embodiment of the present invention relating to an overwriting method when a narrow track is used will now be described with reference to FIGS.
FIG. 4 is a flowchart of the overwriting process according to the first embodiment of the present invention. When overwriting m tracks from the nth track to the mth track, first, in the magnetic disk The free space is checked, and it is checked whether the free space is continuous for 2 × m tracks or more. If there is free space, the free space is recorded in the free area.
In the first embodiment of the present invention, an empty area is set for 3 tracks from the outermost diameter of the magnetic disk, so that the free space is not continuous over 2 × m tracks. Go to the next step.
[0031]
4 and 5A, in the next step, before the information of track n, track n + 1, and track m is overwritten and erased, it is read out and recorded in the empty area 21 in advance, that is, saved. .
It is assumed that the track in which information in the information recording area 22 is already written is the wide track 13 corresponding to the core width of the write head, and the track width in the empty area 21 in this case is The wide track 13 corresponding to the core width of the head may be left as it is.
[0032]
4 and 5B, in the next step, the track n 'is overwritten with the information obtained by correcting the information of the track n on the track n.
In this case, since the track n ′ is in the written state, it remains the wide track 13 corresponding to the core width of the write head.
[0033]
4 and 6C. Next, DC erase is performed using the write head so that the track n ′ partially overlaps in the track width direction of the track n ′, so that the track n ′ composed of the wide track 13 is changed to the narrow track 11. Track n ″ consisting of
In this case, for example, a part of the track n + 1 overlaps with the DC erase area 17 and the information is erased. However, since the information of the track n + 1 has already been saved in the empty area 21, there is no problem.
[0034]
4 and 6D, in the next step, the information of track m + 1 is read out and saved in the portion of track n that has already been overwritten in empty area 21, and the information of track n + 1 is read from empty area 21. By repeating the write-DC erase procedure similar to the procedure for overwriting track n, track n + 1 consisting of wide track 13 is made narrow track n ″ +1 via track n ′ + 1 consisting of wide track 13. Then, for the track m, the track m composed of the wide track 13 is converted into the narrow track m ″ via the track m ′ composed of the wide track 13 in the same manner.
[0035]
In the steps so far, as shown in FIG. 6D, as the track becomes narrower, an empty space 18 corresponding to approximately one track is formed between the next track m + 1 and this empty space. In this state, it becomes a useless area, and the useless space increases as the number of overwriting increases.
[0036]
Accordingly, the number X of overwriting is counted, and it is determined whether or not the number X exceeds the number Y that does not show the superiority of the recording method of the present invention. Exit.
On the other hand, when the number of times of overwriting X exceeds Y, in order to eliminate waste in the magnetic disk space, a re-recording operation described later in FIGS. 7 and 8 is performed.
[0037]
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 region.
[0038]
As described above, in the first embodiment of the present invention, since the continuous empty area is provided in the magnetic disk, it is possible to eliminate the disadvantage that overwriting, which is a disadvantage in the narrow track magnetic recording method, is not possible. .
[0039]
In the above description, all tracks before rewriting are wide tracks. However, this is also applicable to narrow tracks. In this case, the information on the next track is always erased along with rewriting. Therefore, all tracks after the track to be rewritten must be overwritten even when there is no correction, but this is the same as the re-recording operation described later.
[0040]
Next, with reference to FIG. 7 and FIG. 8, the recording repacking operation according to the first embodiment of the present invention will be described. Here, a case where recording repacking is performed in order from the track 1 will be described.
FIG. 7 is a flowchart of the repacking operation according to the first embodiment of the present invention, and FIG. 8 is a schematic explanatory view of a narrow track forming process in the magnetic disk.
See FIG. 7 and FIG. 8A. First, information on track 1, track 2 and track 3 is read and recorded in the empty area 21 in advance.
It is assumed that the track in which information in the information recording area 22 is already written is the wide track 13 corresponding to the core width of the write head, and the track width in the empty area 21 in this case is The wide track 13 corresponding to the core width of the head may be left as it is.
[0041]
Next, the DC erase is performed using the write head so that the track 1 partially overlaps in the track width direction, so that the track 1 composed of the wide track 13 becomes the narrow track 1 ″ composed of the narrow track 11.
In this case, for example, a part of the track 2 overlaps with the DC erase area 17 and the information is erased. However, since the information on the track 2 has already been saved in the empty area 21, there is no problem.
[0042]
7 and 8B. In the next step, the information of the track 2 is read from the empty area 21 and written as a track 2 '(not shown) consisting of the wide track 13 after the narrow track 1 ". After that, a narrow track 2 ″ composed of the narrow track 11 is formed by performing DC erase.
Also in this case, a part of the track 3 overlaps with the DC erase area 17 and the information is erased, but there is no problem because the information of the track 3 has already been saved in the empty area 21.
[0043]
By retreating the empty area 21 and performing the write-DC erase up to the last track, the repacking operation is completed.
By performing such a recording repacking operation, when a useless space is generated due to overwriting, it is possible to eliminate the uselessness, thereby effectively using the entire magnetic disk space.
[0044]
Having thus described the embodiments and reference examples of the implementation of the present invention, the present invention is not limited to the configurations and conditions described embodiment and reference example of implementation, it can be variously modified in the.
For example, the reference example that is the premise of the present invention, and thus the write width W, narrow track width T, inter-track space S, and erase width E in the first embodiment of the present invention are merely examples and are used. The write head and the read head are appropriately changed according to the form or according to miniaturization.
[0045]
In the first embodiment, when overwriting or re-recording is performed, information on the track to be rewritten and information on the next track is provided in a free area provided in advance on the outermost diameter of the magnetic disk. However, it may be provided on the innermost diameter of the magnetic disk, and may be provided on both.
[0046]
In the first embodiment, the vacant area is set to 3 tracks. However, at least 2 tracks are sufficient. For example, in the case of 2 tracks, the vacant area is available as soon as the track n is overwritten. After rewriting track n in the area with track m, it is necessary to overwrite track n + 1.
[0047]
The area where information is saved with overwriting is not limited to an empty area provided in the magnetic disk. For example, a DRAM (dynamic random access memory), SRAM ( A RAM such as a static random access memory) or a FeRAM (ferroelectric RAM) may be provided, and information may be saved in the RAM.
[0048]
Further, such RAM information is not limited to the magnetic disk device, but information may be saved in an information processing device to which the magnetic disk device is attached, such as a personal computer RAM. It is.
[0049]
【The invention's effect】
According to the present invention, since writing and partial DC erase are repeatedly performed using the same write head, a narrow track having a track width narrower than the core width of the write head can be formed. As a result, the maximum storage capacity can be drastically increased, which greatly contributes to the increase in recording density of magnetic recording and reproducing devices such as HDDs. Further, such as backup dedicated disks and large-capacity portable recording media, etc. New applications can be realized.
[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 a reference example as a premise of the present invention.
FIG. 3 is an explanatory diagram of a narrow track when there is a writing blur.
FIG. 4 is a flowchart of an overwrite process according to the first embodiment of this invention.
FIG. 5 is an explanatory diagram up to the middle of a track state in each flow according to the first embodiment of the present invention;
FIG. 6 is an explanatory diagram after FIG. 5 showing the state of a track in each flow according to the first embodiment of the present invention.
FIG. 7 is a flowchart of a recording repacking operation according to the first embodiment of the present invention.
FIG. 8 is an explanatory diagram of a track state in the recording repacking work according to the first embodiment of this invention.
FIG. 9 is an explanatory diagram of a track state in a conventional magnetic recording medium.

Claims (1)

In a narrow track magnetic recording method in a magnetic recording / reproducing apparatus comprising a reproducing head for magnetically reproducing information, a write head for magnetically recording information, and a magnetic recording medium for writing information, At least one of the outermost diameter and the innermost diameter has an empty area of at least two tracks, and forms a narrow track by completely erasing a part of the width direction of the track in which information is written, Repeat the process of writing the next information through the space where the information is completely erased,
In addition, when overwriting m tracks m from the nth track n to the mth track , it is checked whether the free space in the magnetic recording medium is continuous by 2 × m tracks or more.
If there is a continuous free space of 2 × m tracks or more, the free space is overwritten by the narrow track forming method,
If there is no continuous free space of 2 × m tracks or more, information on at least track n and track n + 1 is read and saved in the free area, and then track n ′ is written on track n.
A narrow track n ″ is formed by completely erasing a part in the width direction of the track n ′ in which the information is written,
By sequentially repeating the procedure of writing the next information as the track n ′ + 1 through the space where the information is completely erased until the formation of the narrow track m ″ for the m-th track m,
A narrow-track magnetic recording method, wherein information to be overwritten is overwritten on a track of the information to be overwritten in a state where information to be overwritten is previously saved in the empty area.

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