JPH04324173A - Control system for positioning magnetic disk device - Google Patents

Abstract

PURPOSE:To reduce the quantity of off-track by controlling the feedfoward of the off-track correcting, and thereby to improve the reliability of read and write from/to a magnetic disk device. CONSTITUTION:Preliminarily the quantity of off-track by synchronous runout in all sectors is stored and off-track correcting data is made by imposing the quantity of off-track in a present sector and the quantity of off-track by synchronous runout in a next sector. The feedfoward of the off-track is controlled by the off-track correcting data.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positioning control system for a magnetic disk drive, and more particularly to a positioning control system for a sector servo type magnetic disk drive.

0002

2. Description of the Related Art FIG. 2 is a format diagram showing a sector format of an example of a sector servo type magnetic disk device.

[0003] A sector servo type magnetic disk device is
As shown in FIG. 2, the servo area 11 in a sector has cylinder address information 17 and off-track information 18, and during a seek operation, positioning control is mainly performed using the cylinder address information 17. When on-track, positioning control is performed mainly using off-track information 18.

Factors causing off-track when on-track include synchronous runout caused by eccentricity of the spindle motor, shape change due to temperature, positional deviation between magnetic heads, vibration, etc. The disk device detects the total off-track amount due to all of these factors and feeds it back to correct the positioning control.

[0005]

[Problems to be Solved by the Invention] In recent years, with the progress of miniaturization and higher density of magnetic disk drives, of the above-mentioned off-track factors, off-track due to synchronous runout caused by eccentricity of the spindle motor has become more serious. This is emerging as a problem.

However, in the conventional sector servo type magnetic disk device positioning control system, as mentioned above, the off-track amount can only be sampled for each sector, so the off-track amount is smaller than in the servo surface servo type linear control. This method has the disadvantage that the correction is coarse and therefore difficult to correct when off-track occurs due to a large synchronization runout.

[0007]

[Means for Solving the Problems] A positioning control method for a magnetic disk device of the present invention is a positioning control method for a magnetic disk device using a sector servo method, in which off-track amounts due to synchronous runout of all sectors are stored in advance. The method includes creating off-track correction data by superimposing the off-track amount of the current sector and the off-track amount due to synchronous runout of the next sector, and performing off-track feedforward using the off-track correction data.

[0008]

Embodiments Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a flowchart showing one embodiment of the present invention.

In this embodiment, as shown in FIG. 1, a block 1 for positioning to a target cylinder after a seek operation is used.
, a block 2 for detecting a sector address, and a block 3 for detecting an off-track amount of the current sector.
A block 4 stores the off-track amount due to synchronous run-out of all sectors, a block 5 performs arithmetic processing to overlap the off-track amount of the current sector and the off-track amount due to synchronous run-out of the next sector, and the calculation in block 5 The block 6 performs off-track correction based on the result.

That is, after positioning to the target cylinder is performed by block 1, the sector address of the current sector is detected by block 2. This is because block 5 requires the off-track amount of the sector next to the current sector. This is detected by reading the sector address information 19 of the data area 12 in FIG.

Next, block 3 detects the off-track amount of the current sector. This is detected by reading the off-track information 18 of the servo area 11 in FIG.

In block 4, the amount of off-track due to synchronous runout of all sectors is stored. The off-track amount detection method using synchronous run-out samples the off-track amount of each sector several times, and calculates the average value of the samples to determine the off-track amount of each track. This off-track amount is stored in a non-volatile RAM so that it can be read out at any time.

Next, block 5 calculates off-track correction data. The calculation is performed by adding the off-track amount of the current sector detected by block 3 to the off-track amount due to the synchronous runout of the sector next to the current sector stored in block 4.

In block 6, the off-track correction data calculated in block 5 is transmitted to a drive system such as a voice coil motor to perform off-track correction.

By performing the above operations, it is possible to correct the off-track occurring in the current sector and the off-track due to synchronous runout that is about to occur in the next sector, and the off-track correction Feedforward control can be performed. Also,
Of the off-track that was corrected using conventional feedback control, the component due to synchronous runout is removed.
The amount of feedback correction can be reduced.

In the above-described embodiment, the sector address of the current sector is detected by block 2, but if the sector address can be detected by hardware in advance, control will be simpler.

[0018]

As explained above, the positioning control method for a magnetic disk device of the present invention stores in advance the off-track amount due to synchronous run-out of all sectors, and the off-track amount of the current sector and the next Off-track correction data is created by superimposing the amount of off-track due to synchronous run-out of the sector, and feed-forward control of off-track is performed using this off-track correction data. This has the effect of reducing the amount. Furthermore, since the amount of off-track is small, there is an effect that the reliability of reading and writing of the magnetic disk device can be improved.

[Brief explanation of drawings]

FIG. 1 is a flowchart showing one embodiment of the present invention.

FIG. 2 is a format diagram showing a sector format of an example of a sector servo type magnetic disk device.

[Explanation of symbols]

1 block 2 Block 3 Block 4 Block 5 Block 6 Block 11 Servo area 12 Data area 17 Cylinder address information 18 Off-track information 19 Sector address information

Claims (1)

[Claims] Claim 1: In a positioning control method for a sector servo type magnetic disk device, the amount of off-track due to synchronous run-out of all sectors is stored in advance, and the amount of off-track due to synchronous run-out of the current sector and the amount of off-track due to synchronous run-out of the next sector are stored in advance. 1. A positioning control method for a magnetic disk device, comprising: creating off-track correction data by superimposing a track amount, and performing off-track feedforward control using the off-track correction data.