JPH1091905A - Magnetic disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase a storage capacity of a magnetic disk by highly densifying the track density by way of improving detecting accuracy in raising an upper limit frequency of a position error signal and also improving head positioning accuracy. SOLUTION: The magnetic disk device is equipped with a magnetic disk 10 capable of storing magnetic information including servo information and data information in tracks 12 formed on the surface of the disk and to be freely rotatably held and a magnetic head for writing/reading information on the tracks of the magnetic disk under rotation, and a servo track 14 for positioning the magnetic head in the tracks 12 is formed along a data track 11 on an information storage surface of the magnetic disk 10, and the servo track 14 and the data track 11 appear alternately in the radial direction R of the magnetic disk 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk drive for storing predetermined data information or reading out stored data information, and more particularly to a magnetic head for positioning a magnetic head with respect to an information storage track of a magnetic disk. And a magnetic disk drive in which tracks for storing servo information are formed in the circumferential direction of the magnetic disk.

[0002]

2. Description of the Related Art A magnetic disk device records or reads information on a plurality of concentric circles by rotating a disk-shaped magnetic disk and positioning a magnetic head at an arbitrary radial position on the magnetic disk. With the recent improvement in the performance of computers and other information devices, in such magnetic disk devices, the recording density of the magnetic disk has been increased, and the transfer rate for reading by the magnetic head has been increased. It has been strongly demanded.
In order to meet such demands for higher density and higher speed, it is necessary to control the position of the magnetic head with higher precision and speed.

In order to position the magnetic head, 3.5
Inch and 2.5 inch hard disk (HDD-Ha
2. Description of the Related Art In a small magnetic disk device for an rd Disk Device-), a sector servo method in which positioning servo information is discretely recorded on a part of a recording circle (track) is used. The servo information is composed of various kinds of information, and a discrete servo system for obtaining a position error of the head from the information and controlling the magnetic head so that the position error becomes zero is used.

As shown in FIG. 6, a magnetic disk in a conventional magnetic disk device has a large number of tracks 2 as information recording portions formed along a circumferential direction C of a disk-shaped disk 1. The track 2 is configured to record information for each sector 3 which is a unit of a range defined by any two of the radiuses of the disk, and a servo including information such as positioning for each sector 3 is provided. A servo information recording unit 4 for recording information is provided. Note that the symbol R
Is in the disk radial direction.

FIG. 7 shows details of the servo information recorded on the disk. In FIG. 7, one track 2 is composed of a plurality of sectors 3 continuous in the circumferential direction C. One sector 3 includes a servo information recording unit 41 and a gray code recording unit 5 formed in the radial direction R across the tracks of the disk 1, and a sector information recording unit 6 formed in the circumferential direction C along the track 2. And a data recording unit 7. The gray code recorded in the gray code recording unit 5 is a code for indicating the position of the track facing the head, regardless of the position of the head, at the time of seeking to move the magnetic head in the radial direction. Yes, used for seeking. Following the gray code, servo information is written, and a head position error signal is obtained from the servo information.
Gray code and servo information are written across tracks in the radial direction, while sector information and data information are written for each track.

For writing and reading various kinds of information to and from the disk 1, an MR (Magnet) having a high sensitivity is used.
o-Resistive) head, etc., and the read magnetic gap 8 and the write magnetic gap 9 of this MR head have a size relative to the track 2 as shown in FIG. doing. A thin film head or the like utilizing electromagnetic induction is provided with one which also serves as a read gap 8 and a write gap 9, and its size is about the read gap 8 shown in FIG. The one corresponding to the write gap 9 is not actually provided. The write gap width is slightly smaller than the track width, and the read gap width is smaller than the write gap width.

As described above, the position error signal is generated based on the servo information. However, since the servo information is discretely written on the magnetic disk 1, the servo information actually exists. The position error signal is generated through a window that cuts out the signal only in time. However, since the signal is input in a step-like manner, an excessive response occurs and an error easily occurs. In addition, since there are only a few discretely written signals, there is a problem that it is not possible to sufficiently average and it is difficult to increase the accuracy. Further, since the position error signal can be obtained only discretely, the signal band of the servo information cannot be increased. Since the servo band has a positive correlation with the positioning accuracy, the positioning accuracy can be improved as the servo band is wider, but there is an upper limit of the frequency due to the sampling rate in the discrete position error signal. Therefore, the servo band could not be sufficiently widened.

Further, during head seek, head feed is performed by speed control. However, if the seek speed is increased, the probability of crossing servo information decreases, and the seek time with the head position unknown remains longer. For this reason, the speed error increases, and as a result, it becomes difficult to increase the seek speed.

Further, in order to increase the recording capacity of the magnetic disk drive, it is necessary to increase the track density, but in order to increase the track density, it is necessary to provide a high-precision positioning servo system capable of widening the servo band. There is. For this reason, an error signal with a high upper frequency limit and high accuracy is required. However, in the current discrete sector servo method, since the sampling rate of the position error signal is low, a noise component is large and a high-accuracy positioning operation cannot always be expected. .

[0010]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and it has been proposed to improve the positioning accuracy by increasing the upper limit frequency of the position error signal and to increase the track density. The purpose is to increase the recording capacity of a magnetic disk device by increasing the density.

[0011]

In order to achieve the above object, a magnetic disk drive according to the present invention is capable of storing magnetic information including servo information and data information on tracks formed on the surface of a disk and rotatably storing the magnetic information. A magnetic disk that is held, and a magnetic head that writes and reads information to and from the track of the rotating magnetic disk. A servo information storage track formed in a circumferential direction for storing the servo information for positioning the magnetic head with respect to the track, wherein the servo information storage track and the data information storage track alternate in a radial direction of the magnetic disk; Which is characterized in that

According to a second aspect of the present invention, in the magnetic disk device according to the first aspect, the servo information is substantially continuously stored in the servo information storage track formed in a circumferential direction of the magnetic disk. It is characterized by being written.

According to a third aspect of the present invention, in the magnetic disk drive according to the first aspect, a reproduction frequency for reproducing the servo information is lower than a reproduction frequency for reproducing the data information. There is a feature.

According to a fourth aspect of the present invention, in the magnetic disk drive of the first aspect, the magnetic head is supported by one head slider and has two or more gap portions of a read gap portion and a write gap portion. Has,
The width of the read gap portion is set substantially equal to the combined width of the servo information storage track and the data information storage track formed on the information storage surface of the magnetic disk, and the width of the write gap portion is set to the read gap. The width is set to be smaller than the width of the portion.

According to a fifth aspect of the present invention, in the magnetic disk drive of the fourth aspect, the width of the write gap portion is 80% or less of the width of the read gap portion.

With the above-described configuration, by writing two types of different servo information on two adjacent servo tracks, it is possible to specify which one of the two tracks is. A data track for recording data information is arranged so as to be sandwiched between the two servo tracks. The width determined by one servo track and one data track is the nominal track width. Since the width of the reproducing gap is set to be substantially equal to the nominal track width, if the reproducing head is positioned so as to straddle two servo tracks, two different servo track signals having substantially the same reproducing level are obtained. Can be Therefore, when a difference between two different servo track signals is obtained, a position error signal is obtained, and the read gap can be positioned at a position evenly straddling the two servo tracks.

Since the write gap is smaller than a predetermined ratio of the read gap, for example, 80% or less, if the centers of the two gaps are arranged so that they substantially coincide with each other, the write gap is positioned substantially at the center of the servo track. can do. When data writing is performed in this state, a data track can be formed substantially at the center of the two servo tracks.

Since the read gap is always arranged over both the servo track and the data track, the reproduced signal includes signals from both tracks. Since the lowest frequency is determined, the frequency of the servo signal is set lower than the lowest frequency of the reproduction frequency, so that the servo signal and the data signal can be easily separated simply by passing through the separation filter. it can.

The servo signal is recorded at a single frequency in the circumferential direction of the disk, whereas the reproduction signal is a continuous signal. A position error signal having N (signal-to-noise ratio) can be obtained.

Although sector information and the like can be written in a servo track in the circumferential direction, since the amount of information is relatively large, it is preferable to write the data on a relatively wide data track.

Unlike the sector servo method, the magnetic disk device according to the present invention can always obtain servo information, so that the servo band can be increased substantially without limit. Therefore, it is possible to improve the positioning accuracy of the magnetic head. In addition, since servo information can be always obtained during a seek operation, feed control accuracy can be improved and a seek time can be increased.

As a result, it is possible to improve the position error signal active well, improve the positioning accuracy, increase the track density, and increase the recording capacity of the magnetic disk drive.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the magnetic disk drive according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a plan view schematically showing a magnetic disk 10 of a magnetic disk device according to an embodiment of the present invention.
Is formed, and is divided into sectors 13 by any two radii in the radial direction R. Each track 12 provided in the circumferential direction has a circumferential servo track 14 for recording servo information and a data track 11 for mainly recording data information. The data track 11 includes a gray code recording unit 15 for recording a gray code, a sector information recording unit 16 for recording sector information, and a data recording unit 17 for recording data information.

FIG. 2 is an enlarged schematic diagram showing the details of the above-mentioned configuration. As the magnetic head, a high-sensitivity MR head having a read gap 18 and a write gap 19 or a GMR (Giant Magneto-Resistive) head with higher sensitivity is optimal. In FIG. 2, it is desirable that the center of the read gap 18 and the center of the write gap 19 are basically made to coincide with each other. However, depending on the configuration of the device, a case where the centers of the two gaps are shifted may occur. is there. In this case, it is desirable to offset the centers of both gaps by a fixed amount.

FIG. 2 is a schematic view of the magnetic disk 10 shown in FIG.
One track 13 is shown, and one track 12 is divided into a large number of sectors 13 of several tens. At the head of the sector 13 is provided a gray code recording section 15 in which a gray code is continuously recorded only on the data track 11 in the radial direction. The gray code indicates information such as the track number as described above,
Even if it is divided by the servo track 14 that is continuous with the above, there is no particular problem because the width of the read gap 18 is set wide and the read gap 18 always reads the gray code. In this case, the writing frequency of the gray code is the same as that of the data area, and is set so that it can be separated from the servo information. By doing so, even if the reading of the gray code is divided by the servo track, the division time is short, so that there is substantially no problem with respect to the position error signal.

In the servo track 14, different servo information is written between the adjacent N track and the "N + 1" track. For example, in the embodiment shown in FIG. 2, A servo information is recorded on N servo tracks 14, and B servo information is recorded on an adjacent “N + 1” servo track 14. ing. The A-servo information and the B-servo information are arranged alternately on the N data tracks 11 due to bankruptcy. The servo information is continuously written in both A and B, and the reproduction frequency of each is set to a lower frequency band than the reproduction frequency of the data signal. A servo information and B servo information having different reproduction frequencies may be used,
The frequencies may be the same, and one phase may be opposite to the other. The servo signal is separated by a narrow band filter, but using two different frequencies requires two filters. In this regard, it is preferable that the phase is set to two, that is, the normal phase and the negative phase, because only one filter is required. The opposite phase servo signal has the opposite sign of the reproduced signal. Therefore, when the read gap 18 is completely located at the center of the two adjacent servo tracks, the output becomes zero, and the output becomes zero. In the case where the servo track is shifted, the signal is reproduced such that the signal level of the code of the reproduced signal reproduced from the servo track which is shifted is increased.

Servo signals of the same width are written in the servo tracks of two adjacent tracks.
The sum of the width of one servo track 14 and the width of one data track 11 is the nominal track width. The servo track width is preferably about 20 to 25% of the nominal track width. The width of the read gap 18 is preferably the same as the nominal track width, and the write gap width is preferably a width of about 65 to 70% of the nominal track width, and at most the degree obtained by subtracting the servo track width from the nominal track width. good. The data track 11 is provided with a data sector 13 irrelevant to the servo track 14 continuously formed in the circumferential direction C. The sector information recording section 16 stores the data sector 13 in the same frequency band as the data information. Is added and recorded at the beginning.

FIG. 3 shows a schematic configuration of a signal processing system and a servo system in the magnetic disk drive according to the first embodiment. In FIG. 3, a magnetic head 20 is opposed to a position facing the information recording surface of the magnetic disk 10, and the head 20 is a VCM (Voice Call Motor) 21.
The positioning is controlled by an actuator 22 that is driven and controlled by the actuator. The head 20 is connected to a head amplifier 23 that processes the read signal, and the head amplifier 23 is connected to a high-band filter 24 that filters a reproduced signal of data information and a low-band filter 25 that filters a servo signal. The high-pass filter 24 is connected to the data processing system 26, and the low-pass filter 25 is connected to the servo circuit 27, and outputs a position error signal to the VCM 21.

The operation in FIG. 3 will be described. The signal obtained from the head amplifier 23 is supplied to two high-pass and low-pass filters 24 and 25. The signal passed through the high-pass filter 24 is supplied to a data processing system 26. The signal passed through the low-pass filter 25 is supplied to a servo. V supplied to the circuit 27
The head positioning system including the CM 21 and the like is controlled.

Since the signal processing circuit according to the first embodiment shown in FIG. 3 is configured to process two servo signals having a normal phase and a reverse phase, the low-pass filter is one.
However, two low-pass filters 25 are provided in a type using two different low-band frequencies. FIG. 4 shows a signal processing system of the magnetic disk drive according to the second embodiment when the frequencies of the two servo signals A and B are different. The signal processing system floor of the apparatus according to the first embodiment is that the low-pass filter 25 in FIG. 3 is replaced with a first low-pass filter 25a and a second low-pass filter 25b. is there.

Although the magnetic disk 10 used in the magnetic disk device according to the first embodiment of FIG. 2 has been described as having the servo track 14 continuing in the circumferential direction C of the disk 10 in parallel with the track 12, However, the present invention is not limited to this, and as in the magnetic disk drive according to the third embodiment shown in FIG.
To the servo track 140 and the data track 1
The gray code recording unit 150 that crosses the line 10 may be provided. In such a configuration in which the gray code divides the servo track, the position error signal may be supplied to the switch first. Since the position error signal becomes an error when the magnetic head passes through the gray code recording unit 150, the switch is turned off only during this time, and the signal value immediately before the passage may be given instead. Since this time is extremely short, the influence on the control of the head position is small.

The position error signal is supplied to the actuator 22 via a servo circuit, and adjusts the positional relationship of the head 20 with respect to the disk information recording surface. Since the position error signal is a continuous signal, it does not substantially affect the band of the servo signal, and a servo signal of a high band can be used as long as the detection mechanism allows. Can be higher.

Also, when controlling the seek speed during head seek, the position error signal can be constantly monitored irrespective of the seek speed, so that the seek error can be reduced and the seek speed can be improved.

[0034]

As described above, according to the magnetic disk drive of the present invention, the servo track for recording the servo information for detecting the positioning error with respect to the track of the head is arranged in parallel with the data track. Since they are arranged in the circumferential direction, the frequency band of the position error signal can be increased, and the accuracy of the position error can be dramatically improved. Also, when the magnetic head seeks in the radial direction of the disk, the seek speed can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a plan view showing a magnetic disk of a magnetic disk device according to a first embodiment of the present invention.

FIG. 2 is a partially enlarged view of the magnetic disk shown in FIG.

FIG. 3 is a block diagram of a signal processing circuit of the magnetic disk drive according to the first embodiment.

FIG. 4 is a block diagram of a signal processing circuit of a magnetic disk drive according to a second embodiment.

FIG. 5 is an enlarged plan view showing a magnetic disk according to a third embodiment.

FIG. 6 is a plan view showing a magnetic disk in a conventional magnetic disk device.

FIG. 7 is a partially enlarged view of the magnetic disk shown in FIG. 6;

[Explanation of symbols]

 Reference Signs List 10 magnetic disk 11 data track 12 track 13 sector 14 servo track 18 read gap 19 write gap 20 magnetic head 25 low-pass filter 27 servo circuit

Claims (5)

[Claims] 1. A magnetic disk capable of storing magnetic information including servo information and data information on tracks formed on the surface of a disk and rotatably held therein, and information on the tracks of the rotating magnetic disk. A magnetic head that performs writing / reading of the magnetic disk, the magnetic head being formed along the track on the information storage surface of the magnetic disk in the circumferential direction of the disk, and positioning the magnetic head with respect to the track. A magnetic disk drive comprising a servo information storage track for storing servo information, wherein the servo information storage track and the data information storage track alternately appear in a radial direction of the magnetic disk. 2. The apparatus according to claim 1, wherein said servo information is written substantially continuously in said servo information storage track formed in a circumferential direction of said magnetic disk. Magnetic disk drive. 3. The magnetic disk drive according to claim 1, wherein a reproduction frequency for reproducing the servo information is lower than a reproduction frequency for reproducing the data information. 4. The magnetic head is supported by one head slider and has two or more gap portions of a read gap portion and a write gap portion, and the width of the read gap portion is equal to the information storage surface of the magnetic disk. The width of the write gap portion is set to be substantially smaller than the width of the read gap portion. The magnetic disk drive according to claim 1. 5. The magnetic disk drive according to claim 4, wherein the width of the write gap is 80% or less of the width of the read gap.