JPH0777015B2 - Magnetic disk device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixed magnetic disk having a high recording density and a magnetic head used for the magnetic disk.

2. Description of the Related Art Fixed magnetic disks are becoming higher in density, higher in transfer rate, and faster in access year after year. One of the reasons is that the use of the thin film magnetic head enables the track width to be narrowed and the head to be made smaller and lighter.

In order to further increase the recording density, a magnetic metal thin film is formed by plating or sputtering to obtain a recording medium. The recording wavelength can be reduced with this metal thin film, but in order to take full advantage of its features, it is necessary to reduce the distance between the magnetic head and the recording medium. Continuing to devise a flying head and to develop a technology for cutting the surface of a recording medium substrate at a low cost with a diamond tool. The substrate is made of aluminum alloy, ceramic, glass, or the like.

The track pitch may be narrowed to improve the recording density. However, since the reproduced signal becomes smaller as the track width becomes smaller, efforts are being made to improve the magnetic material of the recording medium and the core material of the thin film head.

Problems to be Solved by the Invention A fixed magnetic disk device includes a large number of disks, and one magnetic head tracks on a control surface. A magnetic head that is driven integrally with the magnetic head,
It is tracked with mechanical accuracy on the other disk surface. Voice coil technology is used to drive the integrated magnetic head in order to increase speed and accuracy. Even if the drag width can be reduced by improving the magnetic material, a high-density magnetic disk with a track pitch of several μm (5K to 10K TPI) cannot be expected by conventional tracking with mechanical accuracy.

Means for Solving the Problems A concentric circle or spiral groove having a constant pitch in the radial direction is formed on a recording medium substrate. A magnetic metal thin film is provided on the substrate to form a recording track between the grooves.

An electrode is integrally formed with the flying magnetic head together with the thin film magnetic head, and means for detecting the electrostatic capacitance between the electrode and the metal thin film is provided.

When the thin-film magnetic head for operation deviates from the recording track between the grooves and comes over the groove, the distance between the electrode and the magnetic metal thin film changes, and the electrostatic capacitance also changes. By detecting this capacitance change, the magnetic head can be controlled so as to track the recording track.

Example 1 Example 1 FIG. 1 shows a cross-sectional view of a recording medium in the radial direction. After the substrate 1 made of aluminum or the like is mirror-cut with a flat diamond cutting tool, the groove 2 is formed into a concentric circle or spiral shape with a V-shaped diamond cutting tool. On top of that, the magnetic metal thin film 3 is deposited by plating or sputtering. For example, groove width 4 is 1μ
m, and the width of the recording track 5 is 4 μm (5K TPI). In this figure, X is the radial direction of the disc.

FIG. 2 shows a sectional view in the circumferential direction of the flying magnetic head. In addition to the thin film magnetic head 6, a metal electrode 7 is provided.
The capacitance between the electrode 7 and the metal magnetic thin film 3 is detected. Y is the disc circumferential direction.

FIG. 3 shows a sectional view of the electrode 7 in the disk radial direction. The electrode 7 is divided into two parts 8 and 9, and an insulating part 10 is provided between them. These divisions 8 and 9
Are each configured to cover the groove portion only slightly, and detect a change in the capacitance between the magnetic metal thin film 3 and each of them independently of each other.

Further, as shown in FIG. 4, the thin-film magnetic head 6 has a core 11
The flying magnetic head is constructed so that the magnetic poles follow the same recording track as the electrode portions 8 and 9. The core 11 does not need to cover the groove. Further, 12 is a thin film coil.

The tracking method will be described. As shown in FIG. 5, when the head moves to the right of the figure (for example, the outer peripheral side of the disk),
The gap between the electrode portion 9 and the magnetic metal thin film 3 becomes large, and the electrostatic capacitance detected by the electrode portion 9 decreases. On the contrary, the capacitance detected by the electrode portion 8 becomes large. At this time, the head is driven so as to move to the left in the figure (inner side of the disk).
On the other hand, although not shown, when the head moves to the inner peripheral side, the capacitance detected by the electrode portion 8 decreases and the capacitance detected by the electrode portion 9 increases. At this time, the head is driven so as to move to the outer peripheral side. As described above, the core 11 of the magnetic head can track the recording track between the grooves.

Example 2 In a large magnetic disk, a groove may be formed for each piece with a diamond bite as in Example 1. However, a small magnetic disk such as a 3.5-inch disk has to be inexpensive, and an easier groove forming method is desired.

Photoresist (for example,
Spin coating of Shipley AZ1350). A groove is formed by covering it with a mask and irradiating it with ultraviolet rays and developing it. The mask can be easily made using laser cutting technology like a video disc. The cross section of the magnetic disk thus formed is as shown in FIG. 13 is a photoresist layer.

Third Embodiment In the first embodiment, the core 11 and the electrode 7 of the thin film head are configured to track on the same recording track 5. However, as shown in FIG. 7, the core 11 and the electrodes 8 and 9 may be configured to track on different recording tracks. In this case, the thin film head and the electrodes are formed on the same plane and side by side in the radial direction of the disk, which facilitates manufacture. Further, since the thin film coil and the electrode are both metals such as aluminum, they can be formed at the same time.

The head shown in FIG. 7 performs tracking similarly to the first embodiment. As shown in FIG. 8, the electrode portions 8 and 9 may be configured to straddle the groove 3, and in this case, tracking is performed in the first embodiment.
When the polarity is reversed, that is, the head shifts to the right in FIG. 8, the electrostatic capacitance detected by the electrode unit 8 decreases, and at this time the head is moved to the left. On the contrary, if the electrostatic capacitance detected by the electrode unit 9 decreases, the head is moved to the right.

As described above, according to the present invention, the track pitch of the magnetic disk can be narrowed to increase the density.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a radial sectional view of a magnetic disk of the present invention, FIG. 2 is a circumferential sectional view of a flying magnetic head of the present invention, and FIGS. Sectional views of the electrode section and the thin film head section of the flying magnetic head, FIG. 5 is an explanatory view of the tracking method, FIG. 6 is a sectional view of a magnetic disk according to a second embodiment of the present invention, and FIGS. It is a magnetic head sectional view of Example 3 of the invention. 1 ... Substrate, 2 ... Groove, 3 ... Magnetic metal thin film, 5 ... Recording track, 6 ... Thin film magnetic head, 7 ... Electrode, 8,9
...... Split electrode part, 10 …… insulation part, 11 …… core, 13 …… photoresist layer.

Claims (2)

[Claims] 1. A magnetic head in which concentric or spiral grooves are formed on a magnetic disk, a recording track is formed between the grooves, and a thin film magnetic head and electrodes are integrally formed. In the magnetic disk device in which the core of the thin film magnetic head tracks the recording track by detecting the electrostatic capacitance between the electrode and the magnetic disk, the electrode is divided into two electrode portions. , An insulating portion is provided between the electrode portions,
Capacitances are independently detected, and the thin-film magnetic head is moved and tracked so that they are equal to each other, and the core portion of the thin-film magnetic head and the electrode are arranged side by side in the radial direction of the magnetic disk. A magnetic disk device characterized in that 2. A magnetic disk drive according to claim 1, wherein the groove on the magnetic disk is formed by mechanically cutting with a diamond bite.