JPS63133366A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To reduce the apparent access time by varying the frequency of detection of position deviation for each data head. CONSTITUTION:A 2nd position information 43 at the outside of a disk 41 and recorded on the magnetic disk 41 or the 2nd position information 44 at the inside is read by data heads 21-23 or the like to detect the deviation of position so as to apply correction attended therewith. When the frequency of detection of position deviation is increased at the head (21-23) apart from a servo head 27, the apparent access time is reduced more in comparison with the case that the same frequency is selected to the heads 21-23 and the position deviation correction is executed quickly.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic head positioning method for a magnetic disk device.

[Conventional technology]

In a conventional magnetic disk drive*rs, when detecting the positional deviation of each data head using the second position information, the frequency is high immediately after the power is turned on, and the temperature change due to self-heating of the magnetic disk drive is small. After that, the position deviation of each data head was detected at time intervals that could follow temperature changes in the external environment. At this time, make sure that the frequency of position deviation detection is the same for each data head.

[Problem that the invention seeks to solve]

However, as shown in FIG.
．． The positional deviation of 23 is mainly caused by the inclination of the main shaft motor 24, the pivot hub 25, and the distortion of the base 7L/-t 26. When used in the prior art described above, the off-track amount of each data head is , the horizontal axis is the time after power-on,
If the vertical axis is the amount of off-track, the result will be as shown in FIG. 3.

34 is the position deviation detection time (all), and 35H is the allowable off-track amount.

For this reason, position deviation detection must be performed at a frequency such that the off-track amount 33 of the data head 25 falls within the allowable off-track range. increase to At this time, if the positional deviations of all data heads are detected at the first positional deviation detection timing, there is a problem in that the waiting time becomes very long and the apparent access time increases.

Therefore, in order to solve these problems, the present invention aims to reduce the frequency of detecting positional deviation of the data head and reduce the apparent access time while satisfying the permissible off-track of the data head. There is.

[Means for solving problems]

In order to solve the above problems, the magnetic disk drive of the present invention is characterized in that the frequency of position deviation detection is changed for each data head as follows.

[Effect]

Detect the position deviation of the data head using the method described above,
If the data heads are positioned, each data head off-track! If the horizontal axis is the time after power-on and the vertical axis is the off-track amount, the result will be as shown in Fig. 1. 1
4 is the positional deviation detection time, and 15 is the allowable off-track amount. There are more timings for position deviation detection than in Figure 3, but in the case of Figure 3, it takes five times to detect the position deviation once compared to Figure 1. . Therefore, the total amount of time required to detect the positional deviation is extremely small.

〔Example〕

The present invention will be explained below based on Examples. Mechanism part 2
It is similar to the figure. Figure 4 shows the data surface. There is a data area 42, which is a collection of data tracks, on the surface of the magnetic disk 41, and σn-e tracks on which second position information 43 and 44 are recorded are located outside and inside the data area 42. The data tracks in the data area and the tracks containing the second position information each correspond to the tracks on the servo surface. Figure 5 is an enlarged view of the second position information. 52 is a chain of burst-like magnetization reversals recorded equidistantly from the center line 53 of the track toward the inner and outer peripheries of the n disks, and the small arrows in the figure indicate that the disks are magnetized by -1! In this embodiment, the pair 51 and 52 is the second position information, and this bear is recorded at eight locations over one round. 54 is the second position information. Although it is a chain of magnetization reversals that fills in the gap, it does not have any meaning as position information.

FIG. 6 shows all the head output waveforms when the data head is shifted toward the outer circumference from the center line 55 and the second position information is read. Regions 61 and 62 are readout waveforms of the magnetization reversal chains 51 and 52, respectively, and region 63 is the readout waveform of the magnetization reversal chains 5.
Corresponds to 4. The data head is deviated toward the outer circumferential side with respect to the track on which the second position information is recorded, and positioning ζ1. In this case, the output waveform of the data head has a small amplitude at the magnetization reversal chain 51 and a large amplitude at the magnetization reversal chain 52, as shown in FIG. The data head may be positioned so that these two amplitudes are equal.

In this embodiment, the reason why the second position information 45 is present one on the inner circumference side and one on the outer circumference side of the data surface is that the amount of positional deviation of the data head generally exists on the inner circumference side and the outer circumference side of the data surface. This is because the positional deviation of these two tracks is changed, and if the positional deviation of the data track is, for example, linearly pushed apart, a good correction result can be obtained.

When performing position correction using this second position information, the access time becomes extremely long because the entire correction amount is measured each time the access is made, so the corrected view is updated at an appropriately determined time interval, and the next In measurement 1 of the correction amount of ft]i!, the previous correction amount is memorized. ! 2 Ru.

The correction interval varies from data head to data head, i.e.
If the correction amount is updated more frequently as the data head is farther away from the servo head, the time spent on determining the correction/measurement will be reduced, and the apparent access time will be shortened. (If the correction amount is being measured at 9 o'clock when you try to access it).

Here, an embodiment regarding the second position information has been shown, but the second position information includes information on the position deviation of the data head.1. It goes without saying that the purpose of the present invention can be achieved using any information.

〔Effect of the invention〕

By using the method described above, the present invention
By reducing the W4 degree of data head position deviation measurement, the apparent access time can be shortened.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the off-track t of each data head of the present invention. FIG. 2 is an explanatory diagram of data head position deviation according to the prior art and the present invention. FIG. 3 is a diagram showing the off-track t of each conventional data head. FIG. 4 is a plan view showing the configuration of a data surface according to the present invention. FIG. 5 is an enlarged view of part 15 of FIG. 1 according to the present invention. FIG. 6 is a waveform diagram for reading position information of $2 according to the present invention. 11... Off-track amount of data head 21 12... Off-track amount of data head 22 15... Off-track of data head 23 Amount 14...... Position deviation detection time 11n'2 15...... Allowable off-track amount 21...
...... Data head 22... Data head 25... Data head 24... Main shaft motor 25... ...Pivot hub 26...Pace great 27...
... Servo head 31 ..... Off-track amount 32 of data head 21 ..... Off-track amount 33 of data head 22 ..... Off-track amount of data head 23 34... Position deviation detection time 55...
・・・・・・Allowable off-track amount 41・・・・・・・・・
Magnetic disk 42...Data area 45...Second position information 44...
. . . Second position information 45 . . . Area 51 shown in FIG. 5 . . . Second position information 52
......Second location information 53...
. . . Track center line 54 . . . Second position information chain of magnetization reversals 61 . . . Readout area 62 of magnetization reversal chain 51 . . . ... Readout area 63 of magnetization reversal chain 52 ... Readout area and above of magnetization reversal chain 54 Applicant Seiko Epson Co., Ltd. Representative patent attorney Tsutomu Mogami and one other person Onisabi, 9 6 ni co (- Fig. 1 Fig. 2 Fig. 2 Ankamihiki insertion i Hikimo embroidery (small ψ9) Fig. 3, ・43 ri 2. d fine coarse''' Fig. 4

Claims (1)

[Claims] at least one servo disk surface on which first position information is recorded for use as a control signal for positioning the data head on a target data track; and a plurality of data on which data and second position information are recorded. at least one servo head disposed in correspondence with the servo disk surface; a plurality of data heads disposed in correspondence with the data disk surface; a control unit that controls the positioning of the data head on the target data track based on the second position information, and determines the position deviation between the data head and the data track by referring to the second position information. In a magnetic disk device that detects and stores each data head, and positions each data head by superimposing the position deviation on a position signal detected from the first position information, the position deviation is detected. A magnetic disk device characterized in that the frequency is changed for each data head.