JPS613322A - Magnetic disc device - Google Patents

Abstract

PURPOSE:To start smoothly rotating a magnetic disc without degrading the floating characteristic of a magnetic head by making the degree of surface roughness of a landing zone of the magnetic disc higher than that of the part other than the landing zone. CONSTITUTION:Though the degree of surface roughness of a read/write zone 21A of a magnetic disc 21 is made lower than the limit degree of surface roughness, where the sticking phenomenon starts to occur, similarly to a conventional device, the degree of surface roughness of a landing zone 21B is made higher than the limit degree of surface roughness. Therefore, the sticking phenomenon between the magnetic disc 21 and a magnetic head 9 does not occur, and the magnetic disc 21 is smoothly started to rotate without bad influences upon the floading characteristic of the head even after the magnetic head 9 is left on the landing zone 21B for a long period.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a magnetic disk device, and particularly to a magnetic disk device in which rotation of a magnetic disk can be started smoothly.

[Prior art]

1 to 5 show magnetic disk drives according to the prior art.

First, in Fig. 1, l is a rotation source such as a spindle motor,
The rotation source 1 is attached to a magnetic disk device housing (not shown), and has a rotation shaft 2 in a vertical direction.

3 is a magnetic disk attached to the rotating shaft 2, and the magnetic disk 3 is divided into a radially inner landing zone 3A and a read/write zone 3B other than the landing zone 3A. Here, as shown in FIG. 2, the magnetic disk 3 includes an aluminum substrate 4 as a base material, a nickel base plating layer 5 laminated on the top surface of the aluminum substrate 4, and a nickel base plating layer 5 laminated on the top surface of the nickel base plating layer 5. The magnetic disk 3 has a surface roughness of 0.2.
It is finished to a near-mirror finish at SRmax or lower.

Reference numeral 7 denotes a positioning mechanism whose tip reaches above the magnetic disk 3 and can be displaced in the radial direction of the magnetic disk 3 by rotation or linear motion.

Further, 8 is a plate spring attached to the tip of the positioning mechanism 7, 9 is a magnetic head attached to the plate spring 8, and the magnetic head 9 is directed toward the upper surface of the magnetic disk 3 by the plate spring 8. is energized. Here, the magnetic head 9 includes a slider 10 and a core 11.

The coil 12 is wound around the core 11.

Next, the operation will be explained. First, in the non-operating state, the magnetic head 9 is stopped on the landing zone 3A as shown in FIG. 3. At this time, the magnetic head 9 is pressed against the upper surface of the magnetic disk 3 by the leaf spring 8. Thereafter, as the rotation source 1 is driven to start rotating the magnetic disk 3, the magnetic head 9 slightly levitates above the magnetic disk 3 against the spring force of the leaf spring 8, while The head 9 is displaced radially outward of the magnetic disk 3 by the positioning mechanism 7 and positioned so as to face a desired track in the read/write zone 3B, resulting in the state shown in FIG.

In this state, the magnetic head 9 writes and reads information in the read/write zone 3B of the magnetic disk 3.

By the way, in the conventional magnetic disk device configured as described above, when the magnetic disk device is not in operation, the magnetic head 9 is pressed against the upper surface of the magnetic disc 3 by the spring force of the leaf spring 8, and the two are attracted to each other. .

Therefore, in order to start rotating the magnetic disk 3, a starting torque TS greater than the load torque TL (expressed by the following equation) is required based on the attraction phenomenon between the two as described above.

TL-μ・F-r (μ: friction coefficient, F: spring force of leaf spring 8, r: average positioning radius) Here, the load torque TL is determined by the surface roughness of the magnetic disk 3 and the magnetic head. 9 changes depending on the time t for which the contact point 9 is left in contact with the landing zone 3A, and the relationship is shown in FIG.

In Figure 5, A indicates when the surface roughness of the magnetic disk 3 is greater than the critical surface roughness, C indicates when the surface roughness is the same as the critical surface roughness, and C indicates that the surface roughness is greater than the critical surface roughness. Each shows when it was small. Note that the critical surface roughness refers to the surface roughness of the magnetic disk 3 when an attraction phenomenon begins to occur between the magnetic disk 3 and the magnetic head 9.

By the way, as shown in the figure, when the leaving time t is less than 24 hours, I to C are almost the same, whereas
It varies greatly over time.

That is, at point A, the load torque TL is almost constant with respect to the standing time t, and at the end, it increases slightly and becomes almost the same as the starting torque TS. On the other hand, in case C, the load torque TL increases significantly and the standing time is 2.
During the period from 4 hours to 48 hours, the load torque TL
exceeds the starting torque TS. Therefore, after 24 hours or more of standing time, the magnetic disk 3 becomes impossible to start rotating, making it difficult to use, and in the case of C, the reliability of starting rotation is significantly reduced. .

Therefore, in order to solve the above-mentioned drawbacks, the magnetic disk 3
It is conceivable to increase the surface roughness of the magnetic disk 3, but this would increase the unevenness and protrusions on the surface of the magnetic disk 3, causing the magnetic head 9 to become rough.
Furthermore, the outermost cobalt magnetic plating layer 6 becomes non-uniform, making it unsuitable for highly accurate writing and reading characteristics.

[Summary of the invention]

The present invention has been made in view of the above-mentioned drawbacks, and by making the surface roughness of the landing zone of the magnetic disk larger than that of the portion other than the landing zone, the flying characteristics of the magnetic head are not deteriorated, and the information An object of the present invention is to provide a magnetic disk device in which rotation of a magnetic disk can be started smoothly without deteriorating write and read characteristics.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to FIGS. 6 and 7. In addition, in the figures, the same reference numerals are used for the same or equivalent parts.

However, 21 is a magnetic disk according to the present invention, and the magnetic disk 2
The surface roughness of the first read/write zone 21A is made smaller than the critical surface roughness as in the prior art, while the surface roughness of the landing zone 21B is larger than the critical surface roughness.

Next, a method for forming the magnetic disk 21 in the present invention will be explained.

First, as shown in FIG. 7, the surface of the magnetic disk 21 has a multilayer structure, and the nickel base plating layer 22 is polished by a lapping process to obtain a predetermined surface roughness. in this case,
In finishing by polishing, the finished surface roughness can be changed by the number of the abrasive tape used, the number of grains used for polishing, the pressing force of the abrasive tape during lapping, the setting conditions of the lapping machine, etc. Further, the lapping process is divided into several steps, and it is possible to gradually move from a condition with a high surface roughness and a high machining speed to a condition with a low surface roughness.

In order to obtain the magnetic disk 21 according to the present invention, the entire surface of the nickel base plating layer 22, which is several microns or more, is finished to a large surface roughness required for the landing zone 21B, and then a small surface is formed only in the read/write zone 21A. It is better to finish it finer so that it has a rougher finish. After that, when a cobalt magnetic plating layer 23 is formed, the cobalt magnetic plating layer 23 becomes 0.
．． Since it is a thin film of 7J microns or less, it has almost no effect on the surface roughness of the nickel base plating layer 22, and therefore the surface roughness of the magnetic disk 21 is as low as that of the nickel base plating layer 22.
It is almost determined by the surface roughness of

Next, to explain the effect, since the surface roughness of the landing zone 21B is large, the magnetic disk 2
The adsorption phenomenon between 1 and the magnetic heel 9 is prevented, and therefore,
Even if the magnetic head 9 is left in contact with the landing zone 21B for a long time, the magnetic disk 21 can smoothly start rotating.

Further, since the surface roughness of the read/write zone 21'A is small, the floating characteristics of the magnetic head 9 during writing and reading of information are not deteriorated, and furthermore, the writing and reading characteristics of information are not deteriorated. In addition, landing zone 21B
may be provided on the outside or in the middle in the radial direction.

〔Effect of the invention〕

As explained above, according to the present invention, the surface roughness of the landing zone of the magnetic disk is made larger than that of the portion other than the landing zone, so that the writing and reading characteristics of information by the magnetic disk and the flying characteristics of the magnetic head are improved. The rotation of the magnetic disk can be started smoothly without causing any deterioration.

[Brief explanation of the drawing]

1 to 5 show a magnetic disk device according to the prior art, in which FIG. 1 is an external view, FIG. 2 is a partial cross-sectional view of a magnetic disk with magnetic heads facing each other, and FIGS. 3 and 4. is an explanatory diagram explaining the operation, FIG. 5 is a diagram showing the action, FIGS. 6 and 7 are related to the present invention, FIG. 6 is a plan view of the magnetic disk, and FIG. 7 is a diagram of the magnetic disk. FIG. DESCRIPTION OF SYMBOLS 1... Rotation source, 7... Head positioning mechanism, 21.
...Magnetic disc, 21A...Read/write zone, 21
B...Landing zone. Note that the same reference numerals are used for the middle part of the figure or corresponding parts. Agent Masu Oiwa A (and 2 others) Figure 3
Figure 4 Figure 5 Figure 6 Figure 7 Procedural amendments showing Yamapaku 12 case Patent Application No. 122508/1989 2,
Title of the invention: Magnetic disk device 3; Person making the amendment: Representative: Hitoshi Katayama Department 4: Agent 5; Column of drawing to be amended. 6. Contents of correction +11 Drawings and Figure 2 will be corrected as shown in the attached sheet. Figure 2 above

Claims (1)

[Claims] A magnetic disk drive, wherein a landing zone is provided on a part of the surface of a magnetic disk rotated by a rotation source, and a head positioning mechanism positions the magnetic head in the landing zone when the rotation of the magnetic disk stops. A magnetic disk device characterized in that the surface roughness of the landing zone of the magnetic disk is greater than that of the portions other than the landing zone.