JPH04368681A - Off-track correction control system - Google Patents

Abstract

PURPOSE:To reduce an error by a proper head position, updating an off-track correction data, detecting a positional deviation and moving a head and trying to read when the error is generated at the time of reading. CONSTITUTION:By the read command of a read/write means 21, a read/write controller 31 reads out a recording and reproducing data 33a, the error is informed to the means 21 at the time of failing to read. Then, a command retry command is issued to a command retrying means 22 by the means 21, and the moving command of the head is issued to a servo controller 32 and the read command is issued to the circuit 31 by the means 22. The circuit 31 reads out again the data 33a, the moving and the read command of the number of fixed times are issued with the means 22 at the time of generating the error again, the moving and the read are tried till to read normally, an off-track correction table 39 is updated by the moving amount of the head at the time of capable of reading normally. Thus, the error is reduced by obtaining the proper head position.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an off-track correction control method for correcting the head position of a magnetic disk drive, and in particular to an off-track correction amount of a servo track for off-track correction provided outside a data recording/reproducing area on a magnetic disk. This invention relates to an off-track correction control method for correcting the head position of a magnetic disk based on the following.

In recent years, as computer processing power has improved, the capacity of magnetic disk drives has rapidly increased and data transfer speeds have increased rapidly. At the same time, the diameter of magnetic disks tends to become smaller in order to reduce the space and power consumption of magnetic disk devices and improve access time. In other words, downsizing of magnetic disk devices (
Down Sizing) tends to progress.

Furthermore, due to the downsizing of magnetic disk devices, the recording density of magnetic disks is also increasing. Therefore, higher precision is also required for head positioning for accessing recorded and reproduced data. For this head positioning, not only mechanical precision but also head positioning control on a commanded track is important.

0004

2. Description of the Related Art Conventionally, off-track correction has been used as a positioning control for accurately positioning a head. This off-track correction was performed as follows. That is, first, a servo track for off-track correction is recorded for each head or cylinder. Next, the magnetic disk device reads the servo track for off-track correction, measures the amount of positional deviation from the reference track, and stores this amount of positional deviation in a RAM or the like as an off-track correction amount. When reading and writing recording/reproduction data, the head is positioned on a commanded track based on the stored off-track correction amount. An example of this is JP-A-54-158207.

[0005]

However, as time passes after the magnetic disk drive is powered on, the position of the head shifts slightly due to temperature rise, vibration, and other factors in the magnetic disk drive itself. Therefore, even if the head is positioned based on the off-track correction amount,
The head will no longer be accurately positioned on the data track. Therefore, there is a problem that an error occurs even when reading is performed, and it is necessary to further perform off-track correction.

[0006] The present invention has been made in view of these points, and when an error occurs during reading, the amount of head position deviation is detected by retrying the command, and the amount of off-track correction is updated. An object of the present invention is to provide an off-track correction control method.

Another object of the present invention is to provide an off-track correction control system that updates the off-track correction amount using a magnetic disk device when an error occurs during reading.

[0008]

[Means for Solving the Problems] FIG. 1 is a diagram illustrating the principle of the present invention that achieves the above object. In the figure, a disk control device 20 is comprised of a read/write command means 21 and a command retry means 22. Further, the magnetic disk device 30 includes a read/write control circuit 31, a servo control circuit 32, an off-track correction table 39, and a magnetic disk 33. The magnetic disk 33 has recording/reproducing data 33a and a servo track 61 for off-track correction.

Based on the read command issued by the read/write command means 21, the read/write control circuit 31:
Recording and reproduction data 33 recorded on the magnetic disk 33
Lead a. Here, if the read fails, that is, if the head is not accurately positioned on the data track, the read/write control circuit 31 notifies the read/write command means 21 of the error. The read/write command means 21 that received the error notification sends the command retry means 2
2, issues a command to retry the command.

Upon receiving the command retry command, the command retry means 22 issues a command to the servo control circuit 32 to move the head, and issues a read command to the read/write control circuit 31. The read/write control circuit 31 reads the recording/reproduction data 33a recorded on the magnetic disk 33 again in response to this read command. If an error occurs again, the command retry means 22 issues head movement commands and read commands a certain number of times, and attempts are made until reading can be performed normally.

When the read is successfully performed, the command retry means 22 issues an off-track correction data update command to the read/write control circuit 31, and the off-track correction table 39 is updated based on the amount of head movement when the read is successfully performed. Perform updates.

FIG. 2 is a diagram illustrating another principle of the present invention that achieves the above object. In the figure, a disk control device 20 is composed of read/write command means 21. As shown in FIG. The magnetic disk device 30 also includes a read/write control circuit 31, a servo control circuit 32, an off-track correction table 39, a magnetic disk 33, and an off-track correction means 34. The magnetic disk 33 records and reproduces data 3
3a and a servo track 61 for off-track correction.

Based on the read command issued by the read/write command means 21, the read/write control circuit 31:
Recording and reproduction data 33 recorded on the magnetic disk 33
Lead a. Here, if the read fails, that is, if the head is not accurately positioned on the data track, the read/write control circuit 31 notifies the off-track correction means 34 of the error.

Upon receiving the error notification, the off-track correction means 34 issues a command to the servo control circuit 32 to move the head to the servo track, and the read/write control circuit 31
Issue a read command to. The read/write control circuit 31 reads the servo information recorded on the servo track in response to this read command. Then, recording and playback data 3
The amount of positional deviation of the head is calculated based on the inter-track distance between the read track 3a and the servo track, and the waveform obtained from the servo information. Also, the off-track correction table 39 is updated based on this positional deviation amount.

Next, based on the obtained head positional deviation amount, the command retry means 22 instructs the servo control circuit 32 to move the head to the track where the original recording/reproducing data 33a is to be read. A read command is issued to the read/write control circuit 31.

[0016]

[Operation] The read/write command means 21 issues a read command to the read/write control circuit 31, and when an error is notified, issues a command retry command to the command retry means 22. Upon receiving the command retry command, the command retry means 22 issues a read command to the read/write control circuit 31.
A head movement command is issued to the servo control circuit 32, and the amount of positional deviation of the head is detected. Furthermore, the off-track correction table 39 is updated based on the detected positional deviation amount.

Further, the read/write command means 21 issues a read command to the read/write control circuit 31. The read/write control circuit 31 that received the read command performs the read,
If an error occurs, an off-track correction command is issued to the off-track correction means 34. Upon receiving the off-track correction command, the off-track correction means 34 issues a read command to the read/write control circuit 31 and a head movement command to the servo track to the servo control circuit 32, and calculates the head movement from the obtained servo information waveform. Calculate the amount of positional deviation. Then, the off-track correction table 39 is updated with the calculated head positional deviation amount.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram explaining the principle of the present invention. In the figure, a read/write command means 21 of a disk control device 20 issues a read command to a read/write control circuit 31 of a magnetic disk device 30 based on a read command from a host computer. The read/write control circuit 31 reads the recording/reproducing data 33a recorded on the magnetic disk 33 in response to this read command. At this time, if the read fails, that is, if the head is not accurately positioned on the data track, the read/write control circuit 31 notifies the read/write command means 21 of the error.

The read/write command means 21, which has received the error notification, issues a command to the command retry means 22 to retry the command. The command retry means 22 receives the command retry command and issues a command to the servo control circuit 32 to move the head. Since the distance between tracks is 10 to 12 μm, this head movement is 0.5 to 2 μm.
This is done every μm. The servo control circuit 32 receives a head movement command and moves the head toward the center of the disk or in a direction opposite to the center.

Further, the command retry means 22 issues a read command to the read/write control circuit 31 after the head movement is completed. The read/write control circuit 31 reads the recording/reproduction data 33a recorded on the magnetic disk 33 again in response to this read command. At this time, the read/write control circuit 31 notifies the command retry means 22 of an error if the read fails, and of normal termination if the read succeeds.

When the command retry means 22 receives the notification from the read/write control circuit 31, if an error occurs, the command retry means 22 moves the head and tries reading again. However, if reading is not successful even after a certain number of read attempts, the command retry means 22 notifies the read/write command means 21 of an error. Upon receiving the error notification, the read/write command means 21 notifies the host computer of the read error.

Further, in the case of normal termination, the read/write command means 21 issues a command to the read/write control circuit 31 to update the amount of positional deviation of the head in the off-track correction table 39 corresponding to the track that has been read.

Finally, the command retry means 22 transfers the acquired recording and reproduction data 33a to the read/write command means 21. Further, the read/write command means 21 transfers the received recording/reproducing data 33a to the host computer.

FIG. 2 is a diagram illustrating another principle of the present invention. In the figure, the read/write command means 21 of the disk control device 20, based on the read command from the host computer,
A read command is issued to the read/write control circuit 31 of the magnetic disk device 30. The read/write control circuit 31 reads the recording/reproducing data 33a recorded on the magnetic disk 33 in response to this read command.

Here, if the read fails, that is, if the head is not accurately positioned on the data track, the read/write control circuit 31 issues a command to the off-track correction means 34 to perform off-track correction. The off-track correction means 34 receives the off-track correction command and issues a command to the servo control circuit 32 to move the head to a servo track located outside the data recording/reproducing area 33a. The servo control circuit 32 receives a head movement command and moves the head to a servo track.

Further, the off-track correction means 34 issues a read command to the read/write control circuit 31 after the head movement is completed. The read/write control circuit 31 reads the servo information of the servo track based on this read command. At this time, the amount of positional deviation of the head is calculated based on the waveform of the read servo information and the distance the head has been moved. and,
A command is issued to the read/write control circuit 31 to update the calculated head positional deviation amount in the off-track correction table 33b corresponding to the track that has been read. Furthermore, a command is again issued to the servo control circuit 32 to move the head to the track where the read has been performed. Thereafter, the read/write command means 21 is notified that the off-track correction has been completed.

Upon receiving the notification that the off-track correction has been completed, the read/write command means 21 sends the read/write control circuit 3
1, a command to read the recording/reproducing data 33a is issued. Then, the read recording/reproducing data 33a is transferred to the read/write command means 21.

Finally, the read/write command means 21 transfers the received recording/reproducing data 33a to the host computer.

FIG. 3 is an overall configuration diagram of the present invention. In the figure, a host computer 10 is a disk controller 20.
control. The disk control device 20 is mainly composed of an MPU (micro processor unit) 23, a bus I/F (bus interface) 24, an I/F
F (interface) 25, ROM 26 and RAM
It has 27.

The MPU 23 is a processor that controls the disk controller 20. The bus I/F 24 controls communication with the host computer 10. The I/F 25 controls communication with the magnetic disk device 30. The ROM 26 stores system programs and the like. RAM27
Data such as an off-track correction amount, command data to the magnetic disk device 30, and input data from the magnetic disk device 30 are stored in .

The magnetic disk device 30 is mainly composed of an MPU 38 and has a read/write control circuit 31, a servo control circuit 32, a magnetic disk 33, a bus I/F (interface) 35, a ROM 36, and a RAM 37.

The MPU 38 is a processor that controls the magnetic disk device 30. The read/write control circuit 31 is
This is a data input/output circuit that records and reproduces processing data on the magnetic disk 33. The servo control circuit 32 is a servo circuit that controls the operation of the head of the magnetic disk 33 and the rotation of the spindle. The magnetic disk 33 includes recording/reproduction data 33a and an off-track correction table 33.
b etc. are stored. I/F 35 is the disk control device 20
Controls communication with. The ROM 26 stores system programs and the like. The RAM 27 stores data such as an off-track correction table 39, data to be stored on the magnetic disk 33, and input data from the magnetic disk 33.

FIG. 4 is a diagram showing the surface of a magnetic disk. That is, it is a diagram showing one of the plurality of magnetic disk surfaces of the magnetic disk 33 in FIG. 3. In the figure, a magnetic disk surface 60 is composed of a servo track 61 and a data recording/reproducing area 62. Further, the data recording and reproducing area 62 stores the recording and reproducing data 33a shown in FIG. 3 and the like.

FIG. 5 is a diagram showing an off-track correction table. In the figure, the off-track correction table 50 includes the direction of track 0 and the amount of off-track correction 51, the direction of track 1 and the amount of off-track correction 52, the direction of track 2 and the amount of off-track correction 53, and the direction of track 3 and the amount of off-track correction. A track correction amount 54, the direction of track 4 and an off-track correction amount 55, . . . , the direction of track n and an off-track correction amount 5n are stored. That is, the direction of correction of the head position corresponding to each track on one magnetic disk surface and the amount of correction thereof are expressed as numerical values and stored.

For example, assume that the head position correction direction is positive (+) toward the center of the magnetic disk surface. At this time, for example, if the head movement command is issued three times from the reference track toward the center of the magnetic disk surface in track 2, "+3" is set in the direction of track 2 and the off-track correction amount 53. Furthermore, if the head movement command is issued five times from the reference track in the direction opposite to the center direction of the magnetic disk surface in track 2, "-5" is set in the direction of track 2 and the off-track correction amount 53. .

FIG. 6 is a flowchart showing the off-track correction operation performed by the disk control device 20. This flowchart represents the off-track correction operation controlled by the command retry means 22 of FIG.

[S1] A command to read the off-track correction amount is issued. That is, the read/write control circuit 31 in FIG.
A command to read the off-track correction amount corresponding to the track specified is issued. Then, the off-track correction amount as an initial value is set as the head positional deviation amount, and the process proceeds to step S2. [S2] Command read operation. That is, a head movement command to the designated track is issued to the servo control circuit 32, and a read command is issued to the read/write control circuit 31. [S3] Check whether the read operation in step S2 has been completed normally. If it ends normally, the off-track correction operation ends; if it ends with an error, the process advances to step S5. [S4] This step represents command retry. Command retry is
Resetting the amount of positional deviation (step S5), read command (step S5), and inspecting the read command (step S6)
It consists of [S5] The amount of positional deviation of the head is reset. That is, adding or subtracting a value corresponding to 0.5 to 2 μm from the current head positional deviation amount,
Proceed to step S5. [S6] Similar to step S3,
Commands read operation. That is, the servo control circuit 32
A head movement command is issued to a position obtained by adding the head positional deviation amount determined in step S3, and a read command is issued to the read/write control circuit 31. [S7] Step S6
The read operation is completed normally. If the process ends normally, the process proceeds to step S8, and if it ends with an error, the process proceeds to step S5. [S8] The off-track correction amount is updated. That is, a command is issued to the read/write control circuit 31 to update the off-track correction amount corresponding to the designated track by using the current head positional deviation amount as the off-track correction amount.

FIG. 7 is a flowchart showing the off-track correction operation performed by the magnetic disk device 30. This flowchart represents the off-track correction operation controlled by the off-track correction means 34 of FIG. 2.

[S1] A command to read the off-track correction amount is issued. That is, the read/write control circuit 31 in FIG.
A command to read the off-track correction amount corresponding to the track specified is issued. Then, the off-track correction amount is set as the initial value of the head positional deviation amount, and the process proceeds to step S2. [S2] Command read operation. That is, a head movement command to the designated track is issued to the servo control circuit 32, and a read command is issued to the read/write control circuit 31. [S3] Check whether the read operation in step S2 has been completed normally. If it ends normally, it ends; if it ends with an error, step S4
Proceed to. [S4] Seek the head to the servo track. That is, a command is issued to the servo control circuit 32 to move the head from the track where the error occurred to the servo track. At this time, the distance the head was moved is memorized. [S5] Servo information recorded on the servo track is read. That is, a read command is issued to the read/write control circuit 31. [S6] Calculate the amount of head positional deviation. That is, the amount of positional deviation of the head is calculated from the waveform from the servo information resulting from the read operation in step S5 and the distance traveled by the head in step S4. [S7] A command to update the off-track correction amount is issued. That is, a command is issued to the read/write control circuit 31 to update the off-track correction amount corresponding to the designated track using the current head positional deviation amount as the off-track correction amount. [
S8] Command read operation. Similarly to step S4,
A head movement command to the designated track is issued to the servo control circuit 32, and a read command is issued to the read/write control circuit 31.

Therefore, if an error occurs during reading, the amount of positional deviation of the head can be detected and the off-track correction table can be updated.

In the above description, the head position correction direction is set to be positive (+) in the direction toward the center of the magnetic disk surface, but it may be positive (+) in the direction opposite to the center direction of the magnetic disk surface. In addition, the off-track correction table is set for each cylinder.
That is, although they are provided for each head, they may be provided for each track on one surface of the magnetic disk.

Further, although the servo track for off-track correction is provided outside the data recording/reproducing area, it may also be provided inside the data recording/reproducing area or inside the data recording/reproducing area.

[0043]

[Effects of the Invention] As explained above, in the present invention, if an error occurs when reading, the head is moved and read is attempted, the amount of head positional deviation is detected, and the off-track correction table is updated. With this configuration, a proper head position can be obtained and errors during reading can be reduced.

Furthermore, if an error occurs when reading, the head is moved to the servo track by the offset correction means of the magnetic disk device, the servo information of the servo track is read, and the servo information is read from the waveform and the distance traveled by the head. Since the head positional deviation amount is calculated and the off-track correction table is updated with the calculated positional deviation amount, an appropriate head position can be obtained and errors during reading can be reduced. In this case, the time required to perform offset correction is shortened.

[Brief explanation of drawings]

FIG. 1 is a diagram explaining the principle of the present invention.

FIG. 2 is a diagram illustrating another principle of the present invention.

FIG. 3 is an overall configuration diagram of the present invention.

FIG. 4 is a diagram showing a magnetic disk surface.

FIG. 5 is a diagram showing an off-track correction table.

FIG. 6 is a flowchart showing off-track correction operations performed by the disk control device.

FIG. 7 is a flowchart showing off-track correction operations performed by the magnetic disk device.

[Explanation of symbols]

20 Disk control device 21 Read/write command means 22 Command retry means 30 Magnetic disk device 31 Read/write control circuit 32 Servo control circuit 33 Magnetic disk 33a Recording and playback data 34 Off-track correction means 39 Off-track correction table

Claims (4)

[Claims] 1. A command for accessing recording/reproduction data (33a) on a magnetic disk (33) and a servo track (61) for off-track correction in an off-track correction control method for correcting the head position of a magnetic disk device. If an error occurs when reading by the read/write command means (21), the read/write command means (21) issues a command to move the head and then retries the command to read. The amount of positional deviation is detected and the off-track correction table (3
9), a disk control device (20) having a command retry means (22) for updating the off-track correction amount, and the magnetic disk (3) having a plurality of disks and heads.
3) and the recording/reproduction data (33a) of the magnetic disk (33) and the off-track correction table (39) according to a command from the read/write command means (21).
) and the command retry means (22), the read/write control circuit (31) accesses the updated off-track correction amount of the magnetic disk (33).
), the magnetic disk device (30) having a servo control circuit (32) for moving the head of the off-track correction control system. 2. A command for accessing recording/reproduction data (33a) on a magnetic disk (33) and a servo track (61) for off-track correction in an off-track correction control method for correcting the head position of a magnetic disk device. a disk control device (20) having read/write command means (21) for performing read/write command means (21), the magnetic disk (33) having a plurality of disks and heads, and the read/write command means (21) or off-track correction means (3).
4) a read/write control circuit (31) accessing the recording/reproducing data (33a) of the magnetic disk (33) and the off-track correction amount updated to the off-track correction table (39); The amount of positional deviation of the head is detected by a command from the read/write control circuit (31), and the off-track correction table (31) is detected.
The off-track correction means (34) updates the off-track correction amount to the magnetic disk (33b) according to a command from the off-track correction means (34).
), the magnetic disk device (30) having a servo control circuit (32) for moving the head of the off-track correction control system. 3. The off-track correction table (39
3. The off-track correction control system according to claim 1, wherein the off-track correction control method is provided for each track of the disk or for each cylinder. 4. The off-track correction table (39
) is provided on a servo track outside the data recording/reproducing area.