JPH0498652A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To prevent beforehand deterioration of performance and failure due to the deformation state by recording information about the flatness of magnetic disks in more than on track on at least one side of plural magnetic disks respectively. CONSTITUTION:The prescribed information is recorded in advance on both sides of the magnetic disk 3 in one track 11 and 12 respectively before being mounted without distortion by clamping. Then, after mounting the magnetic disks 3, 3, 3, 3,..., the information recorded in the tracks 11 and 12 is read by opposite magnetic heads 6, 6,..., and regenerative signals of the individual opposite magnetic heads 6 are compared with each other. By reading the information recorded in the tracks 11 and 12, the deformation states of the all magnetic disks 3 can be known by the mounting states of these magnetic disks 3. Consequently, deterioration of performance and failure of the magnetic disk device due to deformation of disks 3 are prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic disk device that detects deformation states such as surface runout of a mounted magnetic disk.

``Prior Art'' In general, magnetic disks may be distorted and deformed in the radial direction due to the influence of clamping, or may be bent in the circumferential direction and deformed into a cap shape, as shown in FIG. If the magnetic disk is deformed in this way, it may interfere with the recording and reproduction of information, or may interfere with the stable flying of the magnetic head.

Therefore, the surface shape of the magnetic disk, especially the flatness, is 1
It is necessary to make it 0 μm or less.

In particular, for magnetic disks used in large-capacity, high-density recording magnetic disk devices, the flatness of the magnetic disk itself, that is, the flatness without clamping, is ensured at 6 μm or less. However, in the clamping state,
It may be 10 μm or more.

In view of these circumstances, conventionally, the flatness of a magnetic disk incorporated in a magnetic disk device has been measured using a laser interference type flatness needle.

In flatness measurement using this laser interference type flatness needle,
Interference fringes were obtained as shown in FIGS. 6(a) and 6(b). FIGS. 6(a) and 6(b) show an example of measurement using the laser interference type flat course change. FIG. 6(a) shows interference fringes of a magnetic disk with excellent flatness, and almost concentric interference fringes can be seen.

On the other hand, the interference fringes shown in FIG. 6(b) are caused by a magnetic disk with poor flatness and have a complicated pattern.

``Problems to be Solved by the Invention'' Incidentally, a magnetic disk device is generally equipped with a plurality of stacked magnetic disks, and it is necessary to measure the flatness of each magnetic disk. However, with the laser interference flattening method described above, it is only possible to measure the flatness of the topmost magnetic disk after installation;
It was difficult to measure the flatness of the first magnetic disk.

For this reason, even if a magnetic disk other than the topmost one is deformed, this problem cannot be detected.

Further, even if the magnetic disk deforms due to changes over time, the deformation cannot be detected, resulting in the problem that performance degradation and malfunctions caused by the deformed state cannot be prevented in advance.

Additionally, measurement results using laser interference type flat deflection pose a problem in that it is difficult to know whether the flatness level is due to the flatness level of the magnetic disk itself or whether it is due to deformation of the magnetic disk due to clamping. Ta.

This invention was made in view of the above-mentioned problems.
It is an object of the present invention to provide a magnetic disk device that can know the deformation states that occur during and after mounting of all magnetic disks, and can prevent in advance performance deterioration and malfunctions caused by the deformation states.

"Means for Solving the Problem" In order to solve the above-mentioned problem, in the invention according to claim 1, at least one track on at least one side of a plurality of mounted magnetic disks is provided with information regarding the flatness of the magnetic disks. The invention according to claim 2 is characterized in that information is recorded on each of the magnetic disks, in the invention according to claim 1, the information is recorded on each of the magnetic disks before being installed in the device. The invention according to claim 3 is characterized in that, in the invention according to claim 1, the information is read by magnetic heads facing each other across the magnetic disk, and the signals obtained from the magnetic heads are compared. It is characterized by

``Action'' According to the invention according to claims 1 and 2, information regarding the flatness of the magnetic disks is stored in one or more tracks on at least one side of the plurality of magnetic disks before the magnetic disks are mounted in the apparatus. According to the invention described in 3, the above information is read by magnetic heads facing each other with a magnetic disk in between,
The deformation state of the magnetic disk is recognized by comparing the signals obtained from each magnetic head.

"Embodiments" Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing the structure of a magnetic disk device according to an embodiment of the present invention.

In this figure, 1 is a spindle motor and has a hub 2. The hub 2 includes a plurality of magnetic disks 3,
3,3.3 is installed. The magnetic disks 3 are sequentially stacked with spacers 4, 4, 4 in between and held in place by disk clamps 5. In addition, each magnetic disk 3
On the upper and lower surfaces of the magnetic heads 6.6, respectively.・・・
. . . are suspended by separate members (not shown) so as to face each other. Each magnetic head 6 flies above the magnetic disk surface with a minute gap of 0.1 to 0.2 μm, and records information.
Perform playback.

In the magnetic disk drive described above, as shown in FIG. 2, if the surface of the magnetic disk 3 has convex portions 7 or concave portions 8, or if it is deformed in the radial direction due to the influence of clamping, or broken in the circumferential direction. When the magnetic head 6 is deformed into a cap shape, the flying gap 9 of the magnetic head 6 changes, and accordingly, the signal amplitude of recorded or reproduced information also changes as shown in FIG. In these cases, as described above, recording and reproducing information may be hindered, and the stable flying of the magnetic head 6 may be hindered.

Further, as described above, the magnetic disk used in a large-capacity, high-density recording magnetic disk device may have a diameter of 10 μm or more in a clamped state. For this reason, it is essential to measure the flatness of each magnetic disk 3 with the magnetic disks 3, 3, 3.3 attached.

Therefore, in this embodiment, as described above, the magnetic disk 3
We focused on the fact that the amplitude of signals recorded and reproduced on the magnetic disk 3 varies due to changes in the minute gap between the magnetic disk 3 and the magnetic head 6, that is, due to the warpage of the magnetic disk 3 and the surface shape such as convex portions and concave portions. . That is, in this embodiment, as shown in FIG. 4, one or more tracks (
For example, predetermined information is recorded in advance in the numbers 11 and 12) shown in FIG. And magnetic disk 3, 3,
3.3, the magnetic heads 6.6. ...
... reads the information recorded on the track, and compares the reproduced signals of the opposing magnetic heads. Here, an example of the relationship between the reproduction signal of each magnetic head and the state of the magnetic disk corresponding thereto will be described.

(2) If the amplitude levels of reproduction signals of opposing magnetic heads are different, deformation has occurred in the magnetic disk 3.

(2) The amount of whirling (the amount of eccentric rotation) of the spindle motor can be determined by trafting the amplitude of each reproduction signal by the opposing magnetic heads.

In addition, in this embodiment, the outer track 11 of the magnetic disk
By comparing the reproduced signal from the inner track 12 with the reproduced signal from the inner track 12, it is possible to know the degree of warping due to clamping even if only one side of the magnetic head 6 is used.

Furthermore, in this embodiment, by knowing the deformation state of the magnetic disk, maintenance can be performed in advance to prevent fatal problems (such as data loss) caused by deformation during or after installation.

In the above-mentioned embodiment, a magnetic disk device equipped with four layers of magnetic disks has been described, but there may be four or more layers.

"Effects of the Invention" As explained above, according to this invention, before wearing,
Information regarding flatness is recorded in advance on at least one track on at least one side of a magnetic disk that is free from distortion due to clamping, and by reading the information recorded on the track after mounting the magnetic disk, the following effects can be achieved. is obtained.

(1) The deformation states of all magnetic disks can be known with these magnetic disks installed.

(2) Deterioration in performance and malfunctions of the magnetic disk device due to deformation of the magnetic disk can be prevented.

(3) Changes in the amount of runout of the spindle motor can be known, and defects caused by this can be eliminated.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the structure of the main parts of a magnetic disk device according to an embodiment of the present invention, FIG. 2 is a conceptual diagram showing the positional relationship between a magnetic disk and a magnetic head, and FIG. 3 is similar to FIG. FIG. 4 is a conceptual diagram showing an example of a track of a magnetic disk in which information is recorded according to the present embodiment. FIG. 5 is a diagram of a magnetic disk showing deformation due to clamping of the magnetic disk. Cross-sectional view of FIG. 6(a)
and (b) are schematic diagrams showing interference fringes of a magnetic disk with good flatness and interference fringes of a magnetic disk with poor flatness, respectively, obtained by a conventional laser interference type flatness needle. 3.3, 3.3... Magnetic disk, 6.6.・
...6...Magnetic head, 11.12...
····truck.

Claims (2)

[Claims] (1) A magnetic disk device characterized in that information regarding the flatness of a plurality of magnetic disks installed is recorded in one or more tracks on at least one side of the plurality of magnetic disks. (2) The magnetic disk device according to claim 1, wherein the information is recorded on each of the magnetic disks before being installed in the device. (3) The magnetic disk device according to claim 1, wherein the information is read by magnetic heads facing each other with the magnetic disk interposed therebetween, and signals obtained from each magnetic head are compared.