JP2000048501A - Method for reading and writing information of magnetic disk drive, and magnetic disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reading and writing method for information which improves the speed of access to information in the magnetic disk device, and the magnetic disk device. SOLUTION: In the method for reading and writing information from/to a magnetic disks 2 which rotate on the same axis by integrally driving heads 3 for the magnetic disks, the off-track quantities of the respective heads 3 from a reference position are measured and stored in a storage means 7 and when a read/write commands for information of a magnetic disk 2 is given, a head 3 is selected corresponding to the commands, and the off-track quantity of the selected head 3 is read out of the storage means 7, and the quantity is added to the position information on a target track included in the instruction, and the information is read/written from/to the track at the position where the off track quantity has been added.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of reading information from / to a magnetic disk device for reading / writing information by integrally driving a plurality of heads with respect to at least one magnetic disk rotating about the same axis. / Write method and magnetic disk drive.

[0002]

2. Description of the Related Art FIG. 5 is a diagram showing a configuration of a conventional general magnetic disk drive. As shown in FIG. 5, the magnetic disk drive includes a plurality of disks 11, and these disks 11 rotate at high speed about a rotation shaft 12. Magnetic heads 13 (# 0 to #n) for reading / writing data are arranged on the information recording surface of the disk 11, and these heads 13 are integrated in the radial direction of the disk 11 by driving an actuator 14. It is configured to move. The actuator 14 is controlled by the control unit 15. When a target position disk address and a track address at which information is to be read / written are specified from the host device, the control unit 15 selects a head corresponding to the target position and reads a position signal of the selected head to read the position signal. Perform calculations such as PID compensation,
The resultant drive signal is output to the actuator 14 to position the selected head at the target position.

With the recent miniaturization of magnetic disk devices and the increase in track density, the method of writing information to a magnetic disk is based on a conventional method of writing servo information after assembling an HDA (Head Disk Assembly). From the servo track writer (STW) method, a prewrite STW method in which servo information is written in a single disk state and then an HDA is assembled has been used. The pre-write STW method is suitable for information processing on a disk having a high track density because servo information can be written with high precision. However, in the pre-write STW method, the apparatus is assembled after writing the servo information to the disk. Therefore, the head used for writing the servo information to the servo track and the head used for reading / writing the information by the assembled apparatus are used. Is different. Therefore, there is a problem that off-track occurs between the heads due to a mounting error or the like in an assembly process of the apparatus.

[0004]

As described above, in the conventional magnetic disk drive, there is an off-track between heads. Therefore, when switching heads, it is necessary to correct the off-track between heads. For example, when the track pitch is 2 μm and the off-track amount between the heads is 10 μm, it is necessary to move the head by five tracks to access the target track at the time of head switching. Therefore, the conventional magnetic disk drive requires a seek operation for correcting off-track between heads every time the head is switched, and it takes a considerable seek time to access the target track. In particular, when a head switching operation is performed in the same cylinder, a seek operation corresponding to the off-track amount between heads is performed every time the head is switched, so that there is a problem that an expected access speed cannot be obtained.

In the information reading / writing method and the magnetic disk device of the magnetic disk device according to the present invention, the seek time required for switching the head in the magnetic disk device as described above can be shortened, and the target data can be quickly accessed. An object of the present invention is to provide an information reading / writing method for a disk device and a magnetic disk device.

[0006]

According to the present invention, there is provided a method for reading / writing information from / to a magnetic disk apparatus, comprising the steps of: integrally driving a plurality of heads with respect to at least one magnetic disk rotating on the same axis; Read / write information on magnetic disk
In the writing method, an off-track amount from a reference position for each of the plurality of heads is measured and stored in a storage unit, and when an information read / write instruction for the magnetic disk is given, the off-track amount is measured. The head is selected in accordance with the command, the off-track amount of the selected head is read out from the storage means, and the off-track amount is added to the position information of the target track included in the command to obtain the off-track amount. The information is read / written from / to the track at the position to which is added.

As described above, according to the method of the present invention, after assembling the magnetic disk drive and before starting use of the device (for example,
At the time of inspection before product shipment, etc.), the off-track amount from the reference position for all the heads is measured in advance, and this is stored in the storage means. When accessing a location,
A head corresponding to the target position is selected, the off-track amount of the selected head is read out from the storage means, and the head is moved with the position obtained by adding the off-track amount to the original target track position as the actual target position. Read / write information. That is, in the method of the present invention, since the information is read / written by canceling the off-track amount between heads, it is not necessary to correct the off-track amount when switching heads in the same cylinder. Accordingly, since it is not necessary to perform the seek operation of the head, which is conventionally required, it is possible to reduce the time required for accessing the target track.

In the information reading / writing method for a magnetic disk device, it is preferable that a position of one of the plurality of heads is set as the reference position. still,
In this specification, the head-to-head off-track means a displacement of the heads of the apparatus in the seek direction.

In the information reading / writing method for a magnetic disk drive according to the present invention, it is preferable that the storage means is a nonvolatile memory.

Further, the step of measuring the head-to-head off-track amount of each head and storing it in the storage means is performed after the magnetic disk device is assembled and before the magnetic disk device is used (for example, Inspection before shipping etc.)
Try to do it only once. The heads that make up the magnetic disk drive are configured to move integrally, and once the device is assembled, the off-track amount between the heads of each head hardly changes. This is because once the off-track amount from the reference position is set before using the device, it is not necessary to change the off-track amount thereafter.

A magnetic disk according to the present invention to which such an information reading / writing method is applied includes at least one magnetic disk rotating on the same axis and reading of information provided on each information recording surface of the magnetic disk. A head for writing / writing, a driving unit for integrally driving the head, a control unit for controlling the driving unit, and a storage unit for storing an off-track amount from a reference position for each of the heads, When a command for reading / writing information from / to the magnetic disk is given, the control unit selects a head for reading / writing information in accordance with the command, and stores the off-track amount of the selected head. Means for adding the off-track amount to the target track included in the instruction, and adding the off-track amount to the previous position. Characterized in that the selected head is configured to be positioned to read / write information. Also in the case of this device, it is preferable that the storage means is a nonvolatile memory.

[0012]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a diagram showing a configuration of an embodiment of a magnetic disk drive according to the present invention.
As shown in FIG. 1, the magnetic disk drive of the present embodiment
It comprises a plurality of disks 2 that rotate at high speed about a rotating shaft 1. An information recording surface is provided on both surfaces of each disk. Each information recording surface has a magnetic head 3 (# 0 to # 0).
n) are arranged, and these magnetic heads 3 are attached to an actuator 5 via an arm 4. When the actuator 5 is driven, all the heads 3 move integrally to read / write information. I do.
The magnetic disk drive of the present invention further includes a control unit 6 for controlling the actuator 5 and a nonvolatile memory 7, and the nonvolatile memory 7 stores the off-track amounts of the plurality of heads 3. . When the information indicating the target position is given from the host device, the control unit 6 selects the head to be used, reads the off-track amount of the head to be used from the memory 7, and drives the actuator 5 to the corrected position. The head 3 is moved to read / write data.

Writing of the off-track amount of each head 3 to the memory 7 is performed after assembling the magnetic disk device and before the device is actually used, for example, during product inspection before shipment from a factory. FIG. 2 is a diagram showing a process of writing the off-track amount of each head to the memory 7 in the present embodiment. As shown in FIG. 2, first, the # 0 head is positioned at a reference position (that is, a position where the off-track amount is 0) (step 1). Next, with the head 3 fixed at this position, a position signal for each of the heads (# 0 to #n) is read, and the positional deviation between the # 0 head at the reference position and each of the heads, that is, the head The inter-track off-track amount is obtained (step 2).

Next, the measured off-track amount between the heads of the respective heads is written and stored in the nonvolatile memory 7 (step 3). Since the off-track amount of each head hardly changes after the magnetic disk device has been assembled once, the data stored here cannot be rewritten afterwards, and does not disappear even after the power is turned off. FIG. 3 is a diagram showing an example of a storage table in the memory 7. Here, the # 0 head is used as a reference, and the # 1 head is used.
The off-track amount between heads of the head and the # 0 head is three tracks, the off-track amount between heads of the # 2 head is -1 track, and the off-track amount between heads of the #n head is x tracks.

FIG. 4 shows the operation of the magnetic disk drive according to the present invention. The inter-head off-track amount of each head 3 stored in the memory 7 is used as follows. That is, when information indicating a target position (track number and head address) is input from the host device to the control unit 6 (step 1 '), a head corresponding to the target position is selected, and the information is read by the head. The head is switched to perform writing / writing (step 2 '). At this time, the head-to-head off-track amount between the selected head and the # 0 head is read out from the memory 7, the head-to-head off-track amount is added to the target position, and the added position is set as an actual target position. The head 3 is moved (step 3 '). For example, when an instruction to seek the # 1 head and 20 tracks is input to the control unit 6, the control unit 6 switches the head to be used to the # 1 head, and also reads the # 1 head and the # 0 head from the memory 7. Off-track amount of "+
3 "is read out and added to" 20 "to position the head with 23 tracks as the target position. Thus 20
Information that is instructed to read / write on a track will actually be read / written on 23 tracks. At this time, since the off-track amount between the # 2 head and the # 0 head is -1, the #n head is almost at the (20 + x) track at the position of 19 tracks.

Next, from the state in which the # 1 head is positioned on track 20 (actually, it is positioned on track 23 due to the above-described head-to-head off-track correction)
When an instruction to seek the # 2 head to 20 tracks is input, the control unit 6 reads the head-to-head off-track amount "-1" of the # 2 head from the memory 7 and sets the position obtained by adding the read amount to the target track. . That is, the # 2 head performs the positioning operation with 19 tracks as the target position. At this time, since the # 2 head has an off-track between the heads, it is already located at almost 19 tracks.
By simply switching the head, the target track can be accessed without moving the head 3.

As described above, according to the present invention, since the control section 6 sets the position obtained by adding the head-to-head off-track amount to the command from the host device as the target position, the control section 6 controls the head within the same cylinder. When switching and accessing, the position error of the head-to-head off-track amount which has conventionally occurred at the time of head switching is canceled out, and information can be read / written at a desired position without moving the head in practice. Therefore, the seek time is shortened, and the desired track can be accessed quickly.

Although the embodiments of the present invention have been described in detail above, the configuration of the embodiment of the magnetic disk drive according to the present invention is not limited to the configuration of the above-described embodiment. In the above example, the off-track amount of the # 0 head is set to 0, and the off-track amount between heads of the heads to be written as a reference position is corrected. The off-track amount may be corrected.

[0019]

As described above, according to the present invention, the off-track amount of each head is stored in the memory, and when the track is accessed by the head, the off-track amount of the head to be used is read from the memory. The off-track amount is added to the target position given by the host device to determine the actual target position and to read / write information. Therefore, when information is read / written by switching the head in the same cylinder, the target track can be accessed with almost no movement of the head, and the seek time conventionally required can be greatly reduced. .

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of an embodiment of a magnetic disk drive according to the present invention.

FIG. 2 is a diagram illustrating a process of writing data in a memory 7 illustrated in FIG. 1;

FIG. 3 is a diagram illustrating an example of a memory table of a memory 7 illustrated in FIG. 1;

FIG. 4 is a diagram showing steps during the operation of the magnetic disk drive of the present invention.

FIG. 5 is a diagram illustrating a configuration of a conventional magnetic disk drive.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotation axis 2 Disk 3 Head 4 Arm 5 Actuator 6 Control part 7 Memory

Claims (7)

[Claims] 1. A method for reading / writing information from / to a magnetic disk by driving a plurality of heads integrally with at least one magnetic disk rotating on the same axis, wherein each of the plurality of heads The amount of off-track from the reference position is measured and stored in the storage means, and when a command to read / write information from / to the magnetic disk is given, a head is selected according to the command, and the storage means is selected. The off-track amount of the selected head is read out from the above, the off-track amount is added to the position information of the target track included in the command, and the information reading / reading is performed on the track at the position where the off-track amount is added. An information reading / writing method for a magnetic disk device, wherein writing is performed. 2. The information reading / writing method for a magnetic disk drive according to claim 1, wherein a position of one of the plurality of heads is set as the reference position. Information reading / writing method. 3. The information reading / writing method for a magnetic disk device according to claim 1, wherein said storage means is a non-volatile memory. 4. The information reading / writing method for a magnetic disk device according to claim 1, wherein after assembling the magnetic disk device, the off-track amount of each of the heads is set before starting use. An information reading / writing method for a magnetic disk drive, characterized in that the information is measured and stored in the storage means. 5. At least one magnetic disk which rotates on the same axis, a head for reading / writing information provided on each information recording surface of the magnetic disk, and a drive for integrally driving the head Means, a control unit for controlling the driving means, and a storage means for storing an off-track amount from a reference position for each of the heads, and when a read / write instruction of information on the magnetic disk is given, The control unit selects a head for reading / writing information according to the command, and reads the off-track amount of the selected head from the storage unit.
The off-track amount is added to a target track included in the instruction, and the selected head is positioned at a position where the off-track amount is added to read / write information. Magnetic disk device. 6. The magnetic disk drive according to claim 5, wherein a position of one of the plurality of heads is set as the reference position. 7. The magnetic disk drive according to claim 5, wherein said storage means is a non-volatile memory.