JPS59116911A - Magnetic disc - Google Patents

Abstract

PURPOSE:To increase recording capacity by dividing the tracks of a disc wherein servocontrol information is buried in sector unit to small track groups, providing their discriminating regions, and making the shortest wavelength in the record of the entire small track group approximately constant thereby enabling recording at roughly a specified wavelength over the entire surface without changing the peripheral speed of the disc. CONSTITUTION:In the figure, 1, 2, 3 denotes small track groups, 4, 5 denote the discriminating regions of the track groups, 6 denotes a servo-control sector, and 7 denotes a data sector. If the shortest wavelength of the record in each small track group is made approximately constant, the sector length corresponding to the innermost circumference in each group is made roughly the same. There are guard zones 10, 11 on both sides of, for example, a data sector zone 12, in the small track group for each data recording. The figure A shows the relation between the servocontrol sector and the data sector. A two-phase die bit pattern 16 is buried in the servocontrol sector. An erasing part 13 is for detecting the servocontrol sector. It is assumed here that the head is in the 1st small track group. The seek operation in the 1st small brack group is the same as in the case of an ordinary disc device, but the highest moving speed of the head is determined by the servocontrol pattern which is four tracks/sector in the case shown in the figure.

Description

[Detailed Description of the Invention] Technical Field of the Invention] This invention relates to a magnetic disk in which tracking servo information for head positioning is embedded [Technical background of the invention and its problems] Conventionally, the inside of a magnetic disk is I have been reading/writing with the rotation speed constant. If the recording frequency is constant, the recording wavelength is proportional to the track diameter, and is long on the outer circumference side and short and curved on the inner circumference side. Since the shortest recording wavelength of a disk is determined at the innermost circumference, increasing the recording area in the radial direction increases the number of tracks, but on the other hand, the recording density on the outer circumference side decreases significantly, so recording within the disk surface Capacity does not necessarily increase. In fact, in an 8-inch hard disk drive, the recording area is about 25 mm, and the innermost/outermost circumference is f.
J, set to 7 or higher.

Thus, conventional magnetic disk devices do not utilize the disk surface effectively. In order to use the disk surface for M effect, it is sufficient to make the recording wavelength constant over the entire disk surface. In other words, this condition can be achieved if the circumferential speed of the disk is kept constant.

To achieve this, the number of rotations of the disk may be changed depending on the recording track diameter. In fact, a method of keeping the circumferential speed constant in the original disk device has been attempted. but,
It is difficult to implement this method in a magnetic tissue device. This is because the access time of the optical disk device a may be sufficiently slower than the response of the rotary servo system, but the magnetic disk device is required to have an extremely fast access time. Furthermore, since tracking of an optical disk device is performed based on pits or file groups, positioning servo information can be extracted regardless of changes in circumferential speed. On the other hand, in a magnetic disk drive, positioning servo information is expressed by the difference in position information between two tracks; therefore, when the circumferential speed changes, the peak hold period differs, making it impossible to extract accurate servo information. In particular, the embedded servo method (in which servo information is embedded in sector units on the data side)
This servo method does not require a dedicated servo surface, so information can be recorded on both sides of the disk, and it also has advantages such as being able to achieve high track density because thermal off-track due to BB degree gradient does not occur. have)
In order to detect a servo sector, a certain erasing section is provided, but if the circumferential speed changes, the erasing section itself cannot be detected, so servo information cannot be obtained.

Therefore, a method has been proposed in which the recording capacity is increased by changing the deheater transfer speed instead of changing the rotational speed of the disk (Japanese Patent Laid-Open No. 147308/1983). In this method, the tissue surface is divided into a plurality of track groups, and each division includes a smaller number of tracks. Sector division always starts from a reference center line, and using this as a reference, a tachometer and a keyway installed externally are used to distinguish the track group where the head is located and the sector. However, although this method is possible in principle, it requires an external device and is not preferred in practice because it requires mounting accuracy and positional deviations due to temperature and humidity.

[Object of the Invention] In view of the above-mentioned drawbacks of the prior art, the present invention is capable of recording data at a nearly constant wavelength over the entire surface of the disk without changing the circumferential speed of the magnetic disk or a device having an external tachometer or keyway. The purpose of the present invention is to provide a magnetic disk with greatly increased recording capacity.

[Summary of the Invention] The magnetic disk of the present invention has servo information embedded in sector units on the same side as the data recording surface, and when positioning the magnetic head using this information, multiple track groups in the radial direction are embedded. It is divided into small track groups, and each small track group is provided with an area for identifying each small track group and a data area, and the shortest recording wavelength of all the small track groups is made to be approximately constant. be. In this case, the rotational speed of the magnetic disk is kept constant and the recording wavelength is changed instead.

[Effects of the Invention] Therefore, the magnetic disk of the present invention can record the shortest recording wavelength simply by adding a small amount of circuitry, without having to install an external device such as a tachometer or keyway, or changing the rotational speed. Since it can be made almost constant over the entire area, the recording capacity per disk surface can be greatly increased, and its practical effects are extremely large. Also, since the rotation speed of the disk is not changed, it has the advantage of being able to position the magnetic disk regardless of the response of the rotation system.

[Embodiments of the invention] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows one embodiment of the present invention, in which a group of recording tracks is arranged in three
Represents a magnetic disk when it is divided.

In the figure, 1, 2, and 3 are divided small track groups for data recording, 4 is an area for identifying the first small track group and the second track group, and 5 is an area for identifying the second track group and the second track group. 3 is an area for distinguishing the trunk group; 6 is a servo sector for head positioning of the first small track group; 7 is a servo sector for positioning the head of the first small track group
indicates a data sector. The sectors of each small track group are determined so that the amount of information in each sector is constant. At this time, if the shortest recording wavelength in each small track group is approximately constant, the sector lengths corresponding to the innermost circumferences of each small track group will be approximately the same.

FIG. 27 is an enlarged view of a part of the magnetic disk shown in FIG. 1, and each small track group for data recording has guard zones 710 and 11 on both sides of the data zone 12, for example. Each of the small track groups 1, 2, and 3 can be considered to correspond to each surface of a general magnetic disk.

The size of the magnetic disk is 200 mm (8 inch size), the trunk density is 40 tracks/mw, and the linear density is approximately 4.
00 bits/mu, the radius of the outermost recording circumference is 95my+,
The radius of the innermost recording circumference is 50 mm, and the pinch of the small track group is 15+o+. The sector capacity including the servo sector is 323B (the data recording capacity when using the claw cap is 2561B).
3), the third small track group has 48 sectors,! 82
The small track group has 63 sectors, and the first small track group has 77 sectors.

The areas 4 and 5 for identifying each small trunk group can be distinguished by having erased portions of different lengths or by changing the number of tracks. Here, three trunks are used for identifying small truck groups. The guard zone is provided for identification of 0 trunk, seek error, data zone protection, etc., and here, an additional track is allocated to each guard zone. Therefore, the data zone in each small track group is 560 tracks, and the guard zone is 560 tracks x 2. The data recording capacity of this magnetic disk in formant is IIMB for the first track group and 9MB for the second track group.

The third track group is 6.9MB, resulting in a total of 26.9MB/.

Assuming that the innermost circumference of a conventional disk is 70mm and the outermost circumference is g5mm, and performing similar calculations, the number of sectors is 54 and the number of data tracks is 960, so the recording capacity when formatting is 13.2MB/side. becomes. Therefore, the magnetic disk of the present invention can record more than twice as much data as conventional magnetic disks at the same track density and linear density.

In the present invention, the shortest recording wavelength of each small track group is approximately constant, and the rotational speed of the disk is constant.

Therefore, the highest frequency in each track group is different. Figure 1 shows the relationship between the servo sector and the data sector, and a two-phase bias pattern is embedded in the servo sector. In the figure, reference numeral 13 denotes an erasing section, which is used for detecting servo sectors.

Note that pseudo data is written in the data area in advance so that a period longer than the erasing section 13 does not occur.

Reference numeral 14 denotes an AGC section, and 15 denotes a zone detection section, which is capable of detecting a data zone and a guard zone within a range of 135 tracks. 16 is a servo pattern in which a two-phase dibit pattern is embedded.

When the magnetic head is at position 17, if the servo signal at position A and the servo signal at position B are equal in magnitude, it means that the magnetic head is on-track on the O track.

The sector period (time unit) in each small track group is short on the outer circumference and long on the inner circumference. Therefore, since the erasing part in the servo sector and the period from the end of the erasing part to the servo information A, B, C, and D also differ depending on each small track group, there are eight servo decoding circuits corresponding to each small track group. Detection of the erased portion is easy if, for example, a retrigger pull monomultibrator is used. Now, assume that the magnetic head is in the first small track group. The seek operation in the first small trunk group is similar to that of a general magnetic disk device. However, the maximum moving speed of the head is determined by the servo pattern, and in the case of FIG. 3, it is 4 tracks/sector. Next, consider the case of seeking to an arbitrary track in the third track group. Even when moving between small trunk groups, the moving speed of the magnetic head is limited to 4 trunks/sector. Before this, the maximum moving speed of the head in the first track group is faster than the maximum moving speed in the second group of tracks, and similarly, the maximum moving speed in the second group is also faster than that in the third group.

Therefore, when moving the head from the first track group to the third track group, it is sufficient to reduce the moving speed in advance before entering the next track group. Here, the speed is changed in the guard zone.

Conversely, when moving the magnetic head from the third group to the first group, the speed may be increased.

FIG. 4 shows areas 4 and guard zones 9 for identifying each small track group. ] This shows the relationship of 0. Here, the identification area 4 is for three trunks and consists of a 5YNC section 19 and an erasing section. The erase portion in the identification area is set to be longer than the erase portion in the servo sector of any small track group.

The purpose of using three tracks as the identification area is to prevent false detection. By changing the lengths of the erased portions in the identification areas 4 and 5, it is possible to identify the small track group over which the head has passed at any time. In fact, if the length of time for the erased part of 4 is a, then
It is sufficient for the erasing portion of No. 5 to be about 1.5a.

Assume that the magnetic head passes through the second track group and enters the third track group. The maximum moving speed of the head is limited before entering the third track group. Therefore, as soon as the head enters the third group, the speed can be controlled using the signal from the servo sector.

Generally, the speed in the guard zone should be set to about half of the maximum movement speed. As soon as the data zone is detected, the contents of the track counter are internalized and a seek operation is performed to the target track.

As shown above, by using the magnetic disk of the present invention, the recording capacity can be greatly improved compared to the conventional method without changing the rotational speed of the disk by simply adding a small amount of circuitry. It also has the advantage of being fast. In the embodiment of the present invention, a two-phase dipit pattern is embedded in the servo sector, but in order to move the head even faster, track addresses may be embedded in the servo sector.
Alternatively, it is also possible to embed a four-phase servo pattern or the like. Furthermore, there is also a method of using an external speed sensor such as a tacho generator.

In the embodiment of the present invention, the track group is divided into three, but
The number of divisions may be 2, 4 or more. However, increasing the number of rudders and lenients will complicate the circuit and cause loss of the guard zone, so it is better to use a division number of one digit or less. Further, in the embodiment, three tracks are allocated to the track group identification area, but the invention is not limited to this. Further, although the embodiment shows a method of changing the erasing period of the identification area, the number of tracks may also be changed.

For example, 4 in FIG. 2 may have 2 tracks, 5 may have 3 trunks, etc. 2 may be used.

Furthermore, although the present invention has been mainly described using a sector servo, it can be similarly applied to a servo surface servo system. In this case, all small track groups etc. are performed on the servo plane. That is, in FIGS. 2 to 4, data sectors may be treated as being replaced with servo sectors. Furthermore, the present invention can be implemented with various modifications without departing from the spirit thereof.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a magnetic disk according to an embodiment of the present invention having three track groups, FIG. 2 is a partially enlarged view of FIG. 1, and FIG. 3 is a diagram showing the relationship between servo sectors and data sectors. FIG. 4 is a diagram showing the relationship between the guard zone and the track group identification area. 1 to 3...Small tracks for recording data, 4
．． 5. Area for identifying small track groups, 6... Servo sectors, 7. Data sectors, 8-11...
Guard zone, 12... Data zone, 13... Erase section in servo sector, 14... AGC section, 15... Zone detection section, 1
6... Servo pattern, 17... Magnetic head. Agent Patent attorney Noriyuki Chika (and 1 other person) Figure 1

Claims (2)

[Claims] (1) In a magnetic disk in which servo information for positioning the read/write head is embedded sector by sector on the same surface as the data recording surface, the trunk group in the information recording area is divided into multiple small track groups for data recording. A magnetic disk characterized in that a region is provided for identifying each small track group, and the shortest recording wavelength of all the small track groups is approximately constant. (2) The magnetic disk according to claim 1, wherein an erase section corresponding to each small track group is provided in the area for identifying each small track group.