JPH04307481A - Magnetic disk and drive device therefor - Google Patents

Abstract

PURPOSE:To contrive an accurate tracking control by providing a servo pattern having sides protruding from the track to the inner and outer peripheral directions in a servo zone and forming at least one of the sides in the direction crossed with the radius. CONSTITUTION:In a magnetic disk 10 provided with the tracks 1 to record informations and guard bands 1a formed between the tracks, the reproducing output of magnetic head 7 is increased, e.g. to the positive side when the magnetic head 7 comes to the position corresponding to the side 3 of servo pattern 2. Whereas, the output is increased to the negative side in the timing when the magnetic head 7 is passed through the side 4. Consequently, the accurate tracking control of the magnetic head 7 is possible, when the tracking control for the magnetic head 7 is made in accordance with the interval between the positive peak and negative peak of the reproducing output of magnetic head 7.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hard disk for magnetically recording and reproducing information, and a magnetic disk suitable for use in a drive device for the hard disk and a drive device for the same.

0002

2. Description of the Related Art Conventional hard disks have been considered continuous media. That is, a magnetic layer is continuously formed on a substrate, and tracks are formed at predetermined positions of the magnetic layer. However, in the case of continuous media, narrowing the track pitch causes fringing or edge noise. To solve this problem, discrete media has recently been attracting attention.

As shown in FIG. 7, this discrete media has tracks made of magnetic material formed on the disk, and guard bands made of non-magnetic material are formed between the tracks. In this way, information can be recorded and reproduced using a magnetic head having a width wider than the track width, so that the above-mentioned fringing and edge noise can be suppressed.

0004

However, when the track pitch is narrowed in such discrete media, there is a problem that it becomes difficult to accurately position the magnetic head with respect to the track.

The present invention has been made in view of the above situation, and is intended to enable accurate tracking control of a magnetic head.

[0006]

[Means for Solving the Problems] A magnetic disk according to claim 1 is a magnetic disk comprising tracks for recording information and guard bands formed between the tracks. The present invention is characterized in that a servo zone is provided, and the servo zone is provided with a servo pattern having two sides protruding from the track in an inner circumferential direction and an outer circumferential direction, and at least one side is formed in a direction intersecting the radius.

[0007] The magnetic disk drive device according to the second aspect of the present invention has servo zones provided at predetermined intervals on the track.
In a magnetic disk drive device that drives a magnetic disk on which a servo pattern is formed, the two sides protruding from the track in the inner circumferential direction and the outer circumferential direction, and at least one side extends in a direction intersecting the radius. , a detection means for detecting two sides of a servo pattern, and a tracking control means for controlling tracking of a magnetic head that records or reproduces information on a track in accordance with reproduction intervals of the two sides.

[0008]

In the magnetic disk according to the first aspect of the invention, a servo pattern is formed in the servo zone. The servo pattern is formed so that its two sides protrude from the track in the inner circumferential direction and the outer circumferential direction. At least one side thereof is formed in a direction intersecting the radius. Therefore, tracking servo can be performed based on the length of the reproduction interval between these two sides.

Furthermore, in the magnetic disk drive device according to the second aspect of the present invention, two sides of the servo pattern are detected, and the magnetic head is tracking controlled in accordance with the reproduction interval of the two sides. Therefore, accurate tracking control can be performed even if the track pitch is narrow.

0010

Embodiment FIG. 2 shows the basic configuration of an embodiment of the magnetic disk 10 of the present invention. In this embodiment, tracks 1 made of magnetic material are formed on concentric circles, and guard bands 1a made of non-magnetic material are formed between the tracks. And in this example,
One revolution of the disk is divided into four, with a servo zone at the beginning of each area and a data zone following it. A servo pattern, which will be described in detail later, is formed in each servo zone, and a track is formed in the data zone. Information will be recorded on the tracks of this data zone.

FIG. 1 shows an enlarged view of the servo zone of one track. In this embodiment, a servo pattern 2 separated from a track 1 is formed in the servo zone. This servo pattern 2 has a substantially trapezoidal shape, and the two upper and lower sides 5 and 6 in the figure are formed parallel to the track 1. On the other hand, side 3 in the direction that intersects track 1 (protrudes from the track in the outer circumferential direction and inner circumferential direction)
, 4, one side 3 is formed in a direction that coincides with the radius of the magnetic disk 10, and the other side 4 is formed in a direction that intersects with the radius.

Next, the function of the servo pattern 2 will be explained with reference to FIG. Now, when the magnetic head 7 is correctly positioned with respect to the track 1, the center line of the magnetic head 7 coincides with the center line of the track 1 in the width direction. At this time, the magnetic head 7 moves on the radius r of the magnetic disk 10. The servo pattern 2 is magnetized, for example, so that its running direction (side 3 side) is the south pole, and the opposite direction (side 4 side) is the north pole. Such magnetization can be achieved, for example, by applying a predetermined DC magnetic field to the magnetic disk 10.
This can be achieved by rotating.

When the magnetic head 7 comes to a position corresponding to the side 3 with respect to the running magnetic disk 10, the reproduction output of the magnetic head 7 increases, for example, to the positive side. On the other hand, at the timing when the magnetic head 7 passes the side 4, it increases to the negative side. Therefore, the reproduction output changes as shown by curve C in FIG. When a pulse D is generated corresponding to the positive peak and negative peak of the curve C, its length becomes Tr.

On the other hand, if the tracking position of the magnetic head 7 is moved to the outer circumference by Δr with respect to the track 1 (upward in FIG. 3), the radial position becomes r+Δr. At this time, the reproduced output waveform of the magnetic head 7 becomes as shown by curve A, and the width of pulse B corresponding to its positive peak and negative peak becomes T(r+Δr). Since the servo pattern 2 of this embodiment is formed so that the outer circumferential side is narrower than the inner circumferential side, when this width T (r+Δr) is compared with Tr, it is clear that Tr is larger.

Similarly, the magnetic head 7 is connected to the magnetic disk 10.
If it moves to the inner circumferential side (lower side in Fig. 3),
The interval between the positive peak value and the negative peak value of the reproduction output of the magnetic head 7 is larger than Tr. Therefore, it is possible to control the tracking of the magnetic head 7 in accordance with the interval between the positive peak value and the negative peak value of the reproduced output waveform.

When tracking control is actually performed based on the above principle, a configuration as shown in FIG. 4, for example, can be considered. The amplifier 12 outputs the reproduction output of the magnetic head 7 to the peak detection circuit 13. The output of the peak detection circuit 13 is supplied to a T-type flip-flop 14. Integrating circuit 15
integrates the output of the T-type flip-flop 14 and outputs it to the sample-and-hold circuit 16. The A/D conversion circuit 17 A/D converts the output of the sample hold circuit 16, and
It is output to 18. The CPU 18 is an A/D conversion circuit 17
A predetermined control signal is output to the tracking servo circuit 20 via the D/A conversion circuit 19 in response to the input from the tracking servo circuit 20 .

Next, the operation will be explained with reference to the waveform diagram in FIG. The reproduction output of the magnetic head 7 is output from the amplifier 12.
is amplified by As shown in FIG. 5A, the output of the amplifier 12 has a positive peak value and a negative peak value corresponding to sides 3 and 4 of the servo pattern 2 described above. The peak detection circuit 13 detects this positive peak value and negative peak value, and generates a detection pulse (FIG. 5B) synchronized with the peak position.
Output. The T-type flip-flop 14 is triggered by the first pulse supplied by the peak detection circuit 13;
Its output inverts from low level to high level. and,
When the next detection pulse is input, the output level drops from high level to low level again. Therefore, the output of the T-type flip-flop 14 is as shown in FIG. 5C. The width of the output pulse of this T-type flip-flop 14 corresponds to the interval between sides 3 and 4 of the servo pattern 2.

The integrating circuit 15 is a T-type flip-flop 14.
It integrates the pulses supplied from the circuit and outputs it to the sample and hold circuit 16 (FIG. 5D). Sample hold circuit 16
samples and holds the data input from the integrating circuit 15 at the negative edge of the pulse output from the T-type flip-flop 14 (timing of side 4 of servo pattern 2). As a result, the output of the sample and hold circuit 16 becomes as shown in FIG. 5E.

The output of the sample and hold circuit 16 is A/
The D conversion circuit 17 converts the analog signal into a digital signal and supplies it to the CPU 18. The level of data inputted from this sample hold circuit 16 via the A/D conversion circuit 17 is determined by the level of the data inputted from side 3 of the servo pattern 2 described above
and 4 intervals. The CPU 18 compares the value of the data input from the A/D conversion circuit 17 with preset reference data (a value corresponding to the width Tr of the pulse D shown in FIG. 3), and generates a control signal corresponding to the error. D/A
It is output to the tracking servo circuit 20 via the conversion circuit 19. The tracking servo circuit 20 performs tracking control on the position of the magnetic head 7 in response to a control voltage supplied from the CPU 18 via the D/A conversion circuit 19 so that its center line coincides with the center line of the track.

The above operations are performed for each servo zone, and in the data zone the magnetic head is held at a position corresponding to the tracking error signal detected in the immediately preceding servo zone.

FIG. 6 shows another embodiment of the servo pattern. In the embodiment shown in FIG. 1, the side in the running direction is made to coincide with the radial direction, and the side opposite to the running direction is formed so as to intersect with the radius. However, as shown in FIG. 6A, the side in the running direction may be formed to intersect with the radius, and the side 3 on the opposite side to the running direction may be formed to coincide with the radius. Also, as shown in FIG. 6B, both sides 4a, 4
b may be formed to intersect the radial direction. Furthermore, in the above embodiment, the two sides are formed so that the interval becomes shorter from the inner circumferential side to the outer circumferential side, but the two sides are formed so that the interval becomes longer from the inner circumferential side to the outer circumferential side. It can also form two sides.

[0022]

As described above, according to the magnetic disk according to claim 1, servo zones are provided on the track at predetermined intervals, and the servo zone has two sides projecting from the track in the inner circumferential direction and the outer circumferential direction. Since the servo pattern is provided and at least one side thereof is formed in a direction intersecting the radius, tracking control can be performed using the interval between these two sides during reproduction. Therefore,
High density becomes possible.

Further, according to the magnetic disk drive device according to the second aspect, since tracking control is performed in accordance with the playback interval on two sides of the servo pattern, even if it is a discrete medium with a narrow track pitch, It also becomes possible to precisely control the tracking of the magnetic head.

[Brief explanation of drawings]

FIG. 1 is an enlarged plan view showing the configuration of an embodiment of a servo zone of a magnetic disk according to the present invention.

FIG. 2 is a plan view showing the relationship between a servo zone and a data zone in an embodiment of the magnetic disk of the present invention.

FIG. 3 is a diagram illustrating the function of a servo pattern in the embodiment of FIG. 1;

FIG. 4 is a block diagram showing the configuration of an embodiment of the magnetic disk drive device of the present invention.

FIG. 5 is a waveform diagram illustrating the operation of the embodiment of FIG. 4;

FIG. 6 is an enlarged view showing the configuration of a servo zone in another embodiment of the magnetic disk of the present invention.

FIG. 7 is a plan view showing the configuration of a conventional magnetic disk.

[Explanation of symbols]

1 track 1a Guard band 2 Servo pattern 3 to 6 sides 7 Magnetic head 13 Peak detection circuit 14 T-type flip-flop 15 Integral circuit 16 Sample and hold circuit 18 CPU 20 Tracking servo circuit

Claims (2)

[Claims] 1. A magnetic disk comprising a track for recording information and a guard band formed between the tracks, wherein the track is provided with servo zones at predetermined intervals, and the servo zone is provided with a guard band formed between the tracks. What is claimed is: 1. A magnetic disk characterized in that a servo pattern is provided having two sides that protrude further in the inner circumferential direction and the outer circumferential direction, and that at least one side is formed in a direction intersecting the radius. 2. A servo zone provided at a predetermined interval on a track has two sides protruding from the track in an inner circumferential direction and an outer circumferential direction, and at least one side extends in a direction intersecting a radius. In a magnetic disk drive device that drives a magnetic disk on which a servo pattern having sides is formed, a detection means for detecting two sides of the servo pattern, and a detection means for recording or recording information on the track corresponding to a reproduction interval of the two sides. 1. A magnetic disk drive device comprising: tracking control means for tracking and controlling a magnetic head for reproduction.