JPS5987669A - Head positioning system of magnetic disk device - Google Patents

Abstract

PURPOSE:To reduce positional deviation between a data head and the center of track by detecting the distance between each disk and each head by reading a displacement detection area provided on each track and controlling a servo head to minimize the maximum value of deviation between each head and disk. CONSTITUTION:When a base plate 4 is deformed, a straight line 8 connecting data heads is tilted and the deviation of distances 11 and 12 is generated. An amount corresponding to the deviation is sent from a detector 14 to a displacement corrector 17. An average of maximum and minimum values of distances 12 and 11 of displacement is determined and outputted. The signal of a servo head 7 is outputted by a position detector 18 as a positional signal and sent to a head feeding section 21. An average value signal of maximum and minimum values of head displacement, i.e. a correction value is sent to the head feeding section 21, and the head feeding section 21 controls to make the servo head positional signal and the correction value equal.

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention The present invention relates to a positioning control system for a magnetic disk device having a disk exclusively for head positioning and a plurality of data recording disks.

BACKGROUND OF THE INVENTION A head positioning mechanism in a conventional magnetic disk device has a servo disk dedicated to positioning, and the positioning of a data recording head to a track has been performed by connecting the servo head and the data head.

However, the mechanically connected and attached data heads thermally expand due to changes in the temperature of the disk device, resulting in positional deviations from the original data tracks, which affects the recording and reproducing of data. In order to deal with this, we need to create a structure that is less prone to thermal changes, place multiple servo disks in the center of stacked disks to reduce the relative displacement of the data head, and install multiple sector servo areas on the data track. Methods such as providing individual track centers and detecting position information with respect to the center of each track have been adopted. However, there are technical limits to creating a structure that does not cause thermal displacement, and placing the servo disk in the center of the data disk is not effective in terms of productivity, and the difference in the number of disks causes the servo track to be engraved. Device compatibility becomes incompatible, and the sector servo method poses problems such as shortened access time and waiting time when switching heads.

Purpose of the Invention The purpose of the present invention is to detect the distance between each data recording disk and each head by reading a displacement detection area provided on each track, and to detect the distance between each head and disk based on that information. The positional deviation between the data head and the track center is controlled by controlling the servo head so that the maximum value of the deviation is the minimum (that is, the head with the largest deviation before correction and the head with the smallest deviation are symmetrical in positive and negative). The goal is to reduce the

In a magnetic disk device using a plurality of discs, the servo head usually follows the center of the servo track, and the displacement between the data head and the data track generally increases as the data head is farther from the servo head. In the present invention, this deviation is detected and the servo head is moved to the center of the maximum and minimum values by giving a steady displacement and following the movement, thereby reducing the deviation between the head and the track, which is similar to a metallurgy, and recording magnetic recording. It is characterized by improving properties.

Embodiment of the Invention An embodiment of the present invention will be described below with reference to FIG. A plurality of data recording disks 1 and servo disks 2 are rotated around a rotating shaft 3. A servo head 7 and a data head 6 are connected to each other so as to be positioned on a straight line 8 by a head support 5 that is movable via a substrate 4 of the disk device. A straight line 9 connects the centers of each data track, and at the intersection of the straight line and the data surface there is an I? for detecting the track center. The information 16 is recorded in advance. This information is similar to the generally known sector servo information, but is recorded at one location on the track. Figure 1 shows the disk device undergoing thermal expansion, and particularly shows that the substrate 4 is deformed and the straight line 8 connecting the data head, which should coincide with the original data track, is tilted. The distance between each data head and track is distance 11
and 12.

In FIG. 2, the signal output from the data head 6 is sent to the data head position detector 14, and the amount corresponding to the head position deviation distances 11 and 12 is sent to the head displacement corrector 17 through output lines 15 and 16. It will be done. Here, the distance of head displacement is 12.

11. For -1, find the average of the maximum and minimum values up to Xn and add 14 to Gen 20. The signal read out from the servo head 7 is sent to the line 19 as a position signal by the position detector 1.
and sent to the head sending section 21. The head feed section performs follow-up control based on position signals from the servo head. The average value (number M (hereinafter referred to as correction value) of the maximum and minimum values of the previous head displacement is sent to the head feed unit from line 20, and the head is fed so that the servo/rad position signal and the correction value are equal. In this case, the head feed operation is equivalent to a follow-up operation with the correction value as the target, and as a result, the positional deviation of the head from the center of each track is half the difference between the maximum displacement and the minimum displacement of all head deviations. However, the displacement described above has positive and negative values with respect to the head operating direction from the center of the track.

Although the thermal displacement of the substrate 4 is emphasized in FIG. 1, the actual deformation due to heat is extremely complicated at all locations. If the positional deviations between the heads and tracks occur completely irregularly, as described in the previous embodiment, by moving the heads to the position of the average value of the maximum and minimum displacements, Minimize the absolute value of displacement. However, in general disk devices, thermal displacement tends to be larger as the head is farther away from the servo head, so by taking advantage of this property, the head and track for measuring head displacement are set to the set of heads and tracks that are farthest from the servo head, or It is also possible to determine the correction value by position detection using two sets of the closest one and the closest one. Furthermore, there may be a plurality of positional displacement detection areas of the data head recorded on each track in the previous embodiments on one circumference. Alternatively, if a special processing time is provided for position correction, it is also possible to detect positional deviation of the head only at one specific track without providing a position detection area for all tracks on the disk surface.

Effects of the Invention According to the present invention, it is possible to reduce the positional deviation between the data head and the data track. The improvement effect is that when the servo head is misaligned in one direction, a shoulder 1 is created that reduces the misalignment between the head and track center by 1/2 or less, which increases the waiting time when switching heads, which is necessary in the sector servo method. The magnetic recording and reproducing characteristics on the data disk can be improved without any problems.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a state in which a head positioning mechanism related to a disk device is deformed due to heat, and FIG. 2 is a diagram showing a positioning control circuit which is an embodiment of the present invention for correcting data head displacement. Explanation of symbols 1... Data recording disk, 2... Servo disk, 3... Disk rotation axis,
4... Board, 5... Head support stand,
6...Data head, 7...Servo head,
8...Head center line, 9...Track center:
l! 'i'. DESCRIPTION OF SYMBOLS 10... Substrate before undergoing thermal displacement, 11... Data head displacement, 12... Data head rubbing, 16... Head displacement detection area, 14... Data head position detector, 15...・Signal line, 16...Ct@ line, 1
7...Head displacement corrector, 1st...Servo position detector, 19...Signal line, 2o...Signal line, 21
...Head feeding section. Proxy attorney Sokushi Do 1 Interest 11. happiness

Claims (1)

[Claims] In a head positioning method for a magnetic disk device including a positioning servo disk, a plurality of data recording disks, and a head connected and attached to a servo head corresponding to each surface of the magnetic disk, each data recording disk surface A signal that can detect head position deviation from the data track center line on each side is recorded in advance, and the maximum deviation in the positive direction (inner circumference direction of the disk) of each head and other heads are recorded in advance. A head positioning method characterized by moving the position of the servo head so that the maximum deviation in the negative direction (toward the outer circumference of the disk) is approximately equal.