JPH03176872A - Control system for magnetic disk device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control technology for a magnetic disk drive, and particularly to a technology that is effective when applied to external force correction in a head position determination control system.

[Conventional technology]

For example, in a magnetic disk device, which is a type of rotating storage device, a plurality of trunks, which are information recording areas, are arranged concentrically on each recording surface of a magnetic disk as a rotating storage medium. By positioning a head, which is movable in the radial direction along each recording surface of the disk, over a target track, information is recorded and reproduced from the track.

Also, among the tracks provided on the front and back image recording surfaces of a single magnetic disk, or on each of a group of recording surfaces when multiple magnetic disks are fixed coaxially and in parallel, tracks located at the same distance from the center of rotation. A group of tracks with the same diameter is managed using the concept of a cylinder, and information is recorded by sequentially filling in the groups of tracks belonging to each cylinder. This reduces the number of positioning operations (seek operations) of the head group to arbitrary tracks (cylinders) in the radial direction, thereby increasing the efficiency of information recording and reproducing operations on the magnetic disk.

By the way, there are generally variations in external forces such as wind pressure and spring force caused by the rotation of the magnetic disk that act on the head group (head drive mechanism) at a positioning position in an arbitrary cylinder, and there are various variations for each of the seven rings. If positioning is performed by operating force, it is difficult to control the positioning of the head group at high speed and with high precision.

For this reason, conventionally, for example, Japanese Patent Application Laid-Open No. 58-16937
As in the technology disclosed in Publication No. 4, a correction table is provided in which the external force correction information necessary to cancel out the external force at each cylinder position is set, and the position determination for any cylinder is performed. In this case, the external force is corrected by reading correction information corresponding to the cylinder and applying it to the head drive mechanism.

[Problem to be solved by the invention]

However, in the case of the above-mentioned conventional technology, differences in the characteristics of individual magnetic disk drives and factors that change external forces over time, such as temperature changes in the system during operation, are not considered, and the operating time is There is a problem in that the deviation between the correction information held in the correction table and the actual state of the external force increases over time, and accurate correction of the external force cannot be expected using the correction information held in the correction table.

In other words, in recent years, in response to demands for further miniaturization and increased recording density of magnetic disk devices, the mutual spacing between multiple tracks arranged concentrically on a magnetic disk has been reduced. Even small fluctuations in the external force can greatly affect the control characteristics of the head positioning operation. For example, during positioning operation, a steady position deviation (off-track) of the head relative to the target trunk may occur, or the head may be off track. Residual vibrations may occur when the head moves from the above-mentioned seek operation, which moves the head onto the track, to the following operation, which causes the head to follow the center of the rotating track. There is a problem in that the recording/reproducing operation of information is obstructed.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a control technology for a magnetic disk device that can improve operational reliability and performance without being affected by changes in the state of the magnetic disk device over time during operation. There is a particular thing.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[A means of promise to solve problems]

A brief overview of typical inventions disclosed in this application is as follows.

That is, the control method of the magnetic disk device of the present invention uses a magnetic disk in which a plurality of recording areas are provided concentrically,
A head that performs information recording and reproducing operations on the magnetic disk, a positioning mechanism that positions the head with respect to the recording area, and a correction table that records correction information when positioning the head with respect to each of the plurality of recording areas. A control method for a magnetic disk drive equipped with an external force correction value based on the amount of positional deviation of the head with respect to the recording area when the head is positioned in a given recording area at regular or irregular intervals after power is turned on. The external force correction value is used to update at least part of the correction information in the correction table.

[Effect]

According to the control method of the magnetic disk device of the present invention described above, for example, after the power is turned on and the rotation of the magnetic disk becomes stable, seek is performed to all cylinders or a representative cylinder, and tracking is performed for a group of tracks belonging to the cylinder. Based on the off-trunk amount during operation, etc., set the correction information in the correction table corresponding to each cylinder, and thereafter seek to all cylinders or a representative cylinder every time a predetermined time elapses. By updating the correction information in the correction table based on the off-track amount during the following operation for the track group belonging to the relevant cylinder, the position of each individual cylinder Even if the external force acting on a positioning mechanism that performs head positioning changes, the head positioning operation for the target recording area is always performed accurately using correction information that is optimal for the current state of the external force. This improves the operational reliability of the magnetic disk device.

〔Example〕

Hereinafter, an example of a control method for a magnetic disk device according to an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a flowchart illustrating an example of the operation of the control method of the magnetic disk device in this embodiment.
Similarly, FIGS. 3 and 6 are diagrams illustrating an example of the operation thereof, and FIG. 4 is a block diagram schematically showing an example of the configuration of the magnetic disk device in this embodiment.

Further, FIG. 5 is a block diagram showing an example of the operation of the magnetic disk device illustrated in FIG. 4.

First, the configuration of the magnetic disk device of this embodiment will be explained with reference to FIG.

The magnetic disk device of this embodiment includes a head disk assembly (HDA) 100 and a microprocessor 200 that performs overall control operations as described below.

The head disk assembly 100 includes a magnetic disk 101 that is a storage medium, a spindle motor 102 that rotates the magnetic disk 101 at a predetermined speed, and a plurality of not-shown motors provided concentrically on the recording surface of the magnetic disk 101. A head 103 performs recording and reproducing operations of information on a track, and the head 103 is connected to a magnetic disk 1.
It has a voice coil motor (VCM) 104 that performs an operation for positioning at any position in the radial direction of 01.

Connected to the head 103 is a head amplifier 105 that reproduces and amplifies servo data 101a, which will be described later, recorded on the magnetic disk 101.

That is, in the magnetic disk device of this embodiment, for example, the cylinder number (track number) or Servo data 10 in which position signals etc. using burst data are recorded
1a is placed.

An auto gain control amplifier (AGC) 105a is connected to the head amplifier 105, and servo data 101 obtained by the head amplifier 105 is connected to the head amplifier 105.
Signals such as a are further amplified.

The output side of the auto gain control amplifier 105a includes a comparator 105b, a track number demodulation circuit 105c, and a position signal demodulator 105d and A
/D:1 is connected to the microprocessor 200 via the inverter 105e.

That is, the comparator 105b pulses the output of the auto gain control amplifier 7' 105a, and the track number demodulation circuit 105C extracts the track number from the serial pulse train coming from the comparator 105b and outputs the serial number. - After performing parallel conversion, an operation is performed to set it in a register (not shown) that is referenced by the microprocessor 200.

Further, the position signal demodulator 105d demodulates the position signal by peak-holding the burst data output from the auto gain control amplifier 105a at the previous stage, and the position signal is transmitted to the A/D converter 1.
After being digitized in 05e, it is manually input to the microprocessor 200.

On the other hand, the whirlpool coil motor 104 of the head disk assembly 100 is connected to the microprocessor 200 via a D/Δ converter 104a and a power amplifier 104b.

Then, the microprocessor 200 generates a digital signal based on the current position information of the head 103 obtained from the servo data 101a as described above, and information such as the target track (cylinder) position commanded from a host device (not shown). By converting the operation amount issued as 1 to an analog signal via the D/A converter 104a and applying it to the power amplifier 104b, the moving speed and displacement amount of the head 103 by the whistling coil morph 104 are controlled. Seek operation to the desired track (cylinder) or place head 1 on the target track.
03 is followed by a following operation.

Note that a group of circuits that perform normal data recording/reproduction, modulation/demodulation, and error correction are connected to the head 103, but these are not directly related to this embodiment, so we will not discuss them here. Illustrations and explanations are omitted.

FIG. 5 shows a model of the following control system that causes the disk 103 to follow an arbitrary track (cylinder) in the magnetic disk device of this embodiment.

In the figure, 100A is a transfer function in the controlled object (head disk assembly IJ 100 ), and F represents the total external force applied to the controlled object. Further, the microprocessor 200 includes a series compensator 200a realized by software or the like, and this series compensator 200a is matured in the above-mentioned boss signal demodulator 105d, and the A/D converter 1
By functioning as a digital filter using human power from the position signal digitized in step 05e, a manipulated variable corresponding to the positive/gin signal is output to the controlled object 100A.

Furthermore, the microprocessor 200 is provided with an external force correction table 200b in which external force 11 2 correction data 20DC (correction information) for the external force F at each relevant cylinder position is accessed using a cylinder (track) number or the like as an address. , the external force correction signal read out corresponding to each cylinder number is added to the operation amount of the series compensator 200a in a feedforward manner.

Here, if the correction value of the operation amount based on the external force correction data 200C held in the external force correction table 200b does not match the actual external force F at the cylinder position, steady positional deviation during following or seek The transient characteristics during the transition from to to following deteriorate, and undesirable phenomena such as increased residual vibration in the head 103 occur.

Therefore, in the case of this embodiment, the initial setting and updating process of the external force correction data 200C in the external force correction table 200b is performed as follows.

In the following description, for example, 1089 tracks are arranged on each recording surface of the magnetic disk 101.
It is assumed that each track belongs to each of cylinders 0 to 1088 together with trunk groups of the same radius on other recording surfaces.

That is, when the magnetic disk 101 is in a predetermined stable rotational state after the power is turned on, when performing the first zero-zero operation (the operation of causing the head 103 to seek to the O cylinder and follow the O cylinder),
The head 103 is sequentially positioned every 64 cylinders from 1088 cylinders, and external force correction data 200C is appropriately output at each cylinder position.
The operation of finding the external force correction data 200c that minimizes the positional deviation and saving it to a random access memory (RAM) (not shown) in the microprocessor 200 is repeated until 0 cylinders.

Then, when the 0-ring is reached, the 18 cylinder positions measured as described above are further divided into 8 parts, and the external force correction data 200C for each 8-cylinder is calculated using a method such as linear interpolation. Then, an external force correction table 200b as shown in FIG. 6 is created.

This allows the head of each magnetic disk device to
It is possible to eliminate positioning errors of the head 103 due to variations in characteristics inherent in the disk assembly 100 (controlled object 100A) and changes over time in the characteristics, thereby improving the operating characteristics of the positioning control system.

Incidentally, the external force F acting on the controlled object 100A is expected to vary over time during operation due to heat generation of the magnetic disk device, fluctuations in power supply voltage, and the like.

Therefore, as mentioned above, one external force F immediately after the power is turned on
measurement and external force correction table 2 based on the measurement results
With the setting of 00b, good positioning characteristics can be obtained at the beginning of operation, but as time passes, the difference between the actual external force F and the external force correction data 200C set in the external force correction table 200b gradually increases. As a result, there is concern that the positional deviation of the head 103 during following and the aforementioned residual vibrations may occur again in the transient characteristics during the transition from seek to following.

Therefore, in the control method of the magnetic disk device of this embodiment, not only immediately after the power is turned on as described above, but also
After the power is turned on, the external force F is re-measured by causing the head 103 to seek a specific cylinder during the execution of an input/output request command received from a host device, for example, once every two minutes. Based on the result, an operation is performed to update the contents of the external force correction table 200b created at the time of zero friction (immediately after the power is turned on).

An example of such an updating process for the external force correction table 200b will be described below with reference to the flowchart of FIG. 1 and the like.

In the microprocessor 200, for example, a program called a monitor that processes human output commands is running, and upon receiving a command (seek command) from a host device (not shown), the process shown in FIG. 1 is started. .

Note that a timer is running in the background of the monitor, and every two minutes, a two-minute elapsed flag (5 6 ), which will be described later, is set to "1".

Also, between the microprocessor 200 and the host device, there is an interface signal called Commancl (
Seek) Complete-P signal is provided, and the monitor outputs the Command Complete-P signal while executing a command from the host device.
and set it to Hi when the command is completed.
By setting this to gh, the host device can know the timing of issuing a human output command.

First, upon receiving a seek command from the host device, the monitor sets the 5eek Complete-P signal to Low.
Please set it to step 301. ) Then, it is determined whether the two-minute elapsed flag is set to "1" (step 302).

If the two-minute elapsed flag is not set to "1'', a seek is executed to move the head 103 to the cylinder instructed by the seek command (step 303).

When the positioning of the head 103 by seeking to the target cylinder is completed, the 5eek Complete-P signal is set to High to notify the host device that the seek command has been completed (step 304), and the execution of the command is completed. .

In input/output operations with a host device, seek commands are issued relatively frequently, and in many cases apply to the processing in steps 301 to 304.

On the other hand, in step 302, the 2 minute elapsed flag is set to 1#.
If it is determined that the command is set, first, the currently accepted command is saved in the RAM (step 305).

After that, the head 103 is caused to seek the 1088 cylinder located at one end of the cylinder group (step 306),
The external force F at the position of the 1088 cylinder is measured and held (step 307).

Furthermore, a seek is performed to the 576 cylinder located approximately at the center of the cylinder group (step 308), and the 576 cylinder is located approximately at the center of the cylinder group.
The external force F at the position of the ring is measured and held (step 3o9).

Next, a seek is performed to the 0 cylinder located at the other end of the cylinder group (step 310), and the external force F at the 0 cylinder is measured and held (step 311).

The 10 points located at both ends of the cylinder group obtained in this way
88 cylinders, 0 cylinders and 576 in the middle
External force correction data 200 of external force correction table 2° Ob based on the measurement results of external force F at each position of the cylinder
The value of c is corrected (step 312).

In addition, in this modification, 1088 cylinders.

The external force correction data 200c corresponding to rings other than the three points of cylinder 576 and cylinder 0 are corrected by interpolating the values obtained at the three points.

Thereafter, the 2-minute elapsed flag is cleared to "0" (step 313), and the command saved in step 305 is restored from the RAM where it was saved (step 3).
14) Return control to the processing from step 303 onward.

After that, the normal seek command described above is executed (step 304), and after the seek is completed, 5eek
The Complete-P signal is set to the old gh to release the command completion waiting state on the host device side.

Here, FIG. 2 shows position signals and Comm in normal seek and seek including measurement processing of external force F.
A waveform 401 and a waveform 402 represent a normal seek, and a waveform 403 and a waveform 404 represent a seek for measuring the external force F.

That is, in normal seek, the head 103 seeks from cylinder n, where it is currently located, to cylinder m, which is the target specified by the command, in one operation.

On the other hand, the measurement sheet for the external force F is the current n in the section 405.
Seek from cylinder to cylinder 1088, section 406
Measure the external force F in the 1088 cylinder,
In section 407, seek from cylinder 1088 to cylinder 576, in section 408, measure external force F on cylinder 576, in section 409, seek from cylinder 576 to cylinder 0, and in section 410 measure external force F on cylinder 0. Finally, in section 411, the target m cylinders specified by the command are sought.

Further, FIG. 3 shows an example of a change in the external force correction table 200b due to the update process in step 312. In the figure, external force correction data 501 is
This is the state before correction, and the external force correction data 502. External force correction data 5o3. The external force correction data 504 indicates the value obtained in the measurement seek of the external force F in steps 306 to 311. For cylinders 1088, 576, and 0 corresponding to these three measurement points, the previous value of external force correction data 200c is replaced by the external force correction data 502, 503, and 504, and the values corresponding to the other cylinder positions are replaced. The value of the external force correction data 200c is calculated by interpolation based on the above three data, and a table of external force correction data 505 is created.

Then, in subsequent seek operations of the head 103 to any cylinder, correction control is performed using the updated external force correction data 505.

As explained above, according to the control method of the magnetic disk device in this embodiment, in the first zero-zero operation immediately after power-on, the external force in the external force correction table 200b is In addition to setting the correction data 200C, from then on, for example, once every 2 minutes, in addition to the normal seek operation, the external force correction data 200C corresponding to the current external force F is set.
The content of the external force correction table 200b is updated by performing the measurement operation, so differences in operating characteristics specific to individual magnetic disk drives and changes over time in the operating characteristics that affect the positioning accuracy of the head 103 are avoided. Not only can it be corrected, but also it is possible to accurately correct changes over time in the external force F caused by changes in temperature and power supply voltage during operation.

This eliminates concerns such as the decay waiting time of residual vibration of the head 103 that occurs due to incomplete correction of the external force F, and the occurrence of off-track during following. Seeking and following to any cylinder can be performed more accurately in a shorter time, improving performance such as the reliability of the operation of the magnetic disk device and the amount of data transferred per unit time.

Furthermore, even if the spacing between a plurality of tracks concentrically arranged on the magnetic disk 101 becomes narrower, each individual track
The positioning of the head 103 with respect to the cylinder can be performed accurately at all times, and it is possible to easily respond to the miniaturization of the head disk assembly 100 and the increase in the recording density of information on the magnetic disk 101.

In addition, since the external force measurement seek is performed in addition to the normal command execution processing from the host device, it can be processed in the same way as a normal seek, and no changes are required to the software on the host device. The advantage is that there is no need to add

Furthermore, since the frequency of execution of external force measurement seeks is extremely low compared to the frequency of execution of seeks in normal input/output operations, the deterioration in the average access time for data recorded on the magnetic disk 101 can be almost ignored. can.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the Examples and can be modified in various ways without departing from the gist thereof. Nor.

For example, in the explanation of the above embodiment, as an example of a method for executing an external force measurement seek, a case was explained in which the external force measurement seek is performed in addition to the execution of a seek command from a host device. Needless to say, a method may be adopted in which the magnetic disk device side spontaneously executes the external force measurement seek at a desired period.

〔Effect of the invention〕

Among the inventions disclosed in this application, the effects obtained by typical inventions are briefly described below.

That is, according to the control system for a magnetic disk device according to the present invention, a magnetic disk having a plurality of concentric recording areas, a head for recording and reproducing information on the magnetic disk, and a head for recording and reproducing information on the magnetic disk are used. A control system for a magnetic disk device comprising: a positioning mechanism for positioning a head with respect to the recording area; and a correction table in which correction information for positioning the head with respect to each of the plurality of recording areas is recorded, the control method comprising: a power supply; After the input, an external force correction value is measured based on the amount of positional deviation of the head with respect to the recording area when the head is positioned in the arbitrary recording area at regular or irregular intervals, and this external force correction value is used to Since at least part of the correction information in the correction table is updated, for example, after the power is turned on and the rotation of the magnetic disk becomes stable, seek to all cylinders or a representative cylinder, and track the tracks belonging to the cylinder. The correction information in the correction table corresponding to each cylinder is set based on the off-track amount during the following operation for the group, and thereafter, the correction information for all cylinders or a representative cylinder is set every time a predetermined time elapses. By seeking to the cylinder and updating the correction information in the correction table based on the off-trunk amount during follow ink operation for the track group belonging to the cylinder, the Even if the external force acting on the positioning mechanism that positions the head at each cylinder position changes, the head positioning operation for the target recording area is always performed using correction information that is optimal for the current state of the external force. This can be done accurately and the reliability of the operation of the magnetic disk device is improved.

[Brief explanation of drawings]

FIG. 1 is a flowchart illustrating an example of the operation of a control method for a magnetic disk device according to an embodiment of the present invention, FIG. 2 is a diagram illustrating an example of the operation, and FIG.
Similarly, FIG. 4 is a block diagram schematically showing an example of the configuration of a magnetic disk device that executes a control method according to an embodiment of the present invention, and FIG. 5 is a diagram explaining an example of its operation. An explanatory diagram showing a modeled example of the configuration of a following control system in a magnetic disk device which is an embodiment of the invention, FIG. 6 is an example of the operation of a control method of a magnetic disk device which is an embodiment of the invention. FIG. 100...Head disk assembly (HDA)
, 100Δ... Controlled object (head disk assembly 'J), 101... Magnetic disk, 101a...
・Servo data, 102... Spindle motor, 10
3...Head, 104...Voice coil motor, 1
04a...D/A converter, 104b...Power amplifier, 105...Head amplifier, 105a...Auto gain control amplifier, 105b...
Comparator, 105C...Track number demodulation circuit,
105d...Position signal demodulator, 105e...
A/D converter, 200... microprocessor,
200a...Series compensator, 200b...External force correction table, 200C...External force correction signal, 301-314
. . . A step showing an example of a processing procedure when performing an external force measurement seek in addition to normal seek command processing, 401 . . . Waveform of position signal during normal seek, 402 . . . Comm
and Complete-P signal waveform, 403...
・Waveform of position signal in external force measurement seek, 40
4...Command C in external force measurement seek. waveform of the mplete-P signal, 405... section for seeking from the current cylinder to 1088 cylinders, 406...
...section where external force is measured with 1088 cylinders, 407
...Seek section from cylinder 1088 to cylinder 576, section where external force is measured at cylinder 408...576, section where cylinder 409...seeks to cylinder 0 from cylinder 576, section where external force is measured at cylinder 410...0 cylinder section, 411...section for seeking from cylinder 0 to target cylinder, 501...external force correction data before external force measurement (state of external force correction table), 502-504...
External force correction data of 0, 576° 1088 cylinders determined by external force measurement, 505... External force correction data (state of external force correction table) obtained by interpolation after external force measurement, F... External force.

Claims (1)

[Claims] 1. A magnetic disk having a plurality of concentric recording areas, a head for recording and reproducing information on the magnetic disk, and a positioning mechanism for positioning the head with respect to the recording area. and a correction table in which correction information for positioning the head with respect to each of the plurality of recording areas is recorded, the control method for a magnetic disk device comprising: a correction table in which correction information for positioning the head with respect to each of the plurality of recording areas is recorded; An external force correction value is measured based on the amount of positional deviation of the head with respect to the recording area when positioning the head in the recording area, and at least part of the correction information in the correction table is corrected using the external force correction value. A control method for a magnetic disk device characterized by updating. 2. A control system for a magnetic disk drive according to claim 1, wherein the period for measuring the external force correction value is made relatively short immediately after power is turned on, and becomes longer as time passes.