Dynamic magnetic information storage or retrieval – Head mounting – Disk record
Reexamination Certificate
2000-09-05
2002-12-17
Evans, Jefferson (Department: 2652)
Dynamic magnetic information storage or retrieval
Head mounting
Disk record
C360S246400, C360S237000
Reexamination Certificate
active
06496332
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
A head slider for a flexible magnetic disk according to the present invention relates to a slider of a magnetic head for performing record to and/or reproduction from the flexible magnetic disk made of a resin substrate on which a magnetic layer is formed, in particular, relates to a technique for realizing a flexible magnetic disk having a higher density and the transfer rate of data at a higher speed together with aiming lower power consumption.
2. Description of the Related Art
Recently, as the performance of a computer is improved and various application areas of the flexible magnetic disk such as a digital camera expand, the recording density of a removable flexible magnetic disk represented by a 3.5-inch floppy disk is increased. Consequently, the improvement of a data transfer rate by means of a change of the speed of revolution of the flexible magnetic disk to be high is required.
On the other hand, from a point of view for loading on a portable personal computer, there is conversely required a head slider capable of performing stable record and stable reproduction under a condition of a low speed of revolution of the flexible magnetic disk where the consumption electric power of a flexible magnetic disk apparatus can be saved, and capable of performing the stable record and the stable reproduction with a low frictional force because the strength of the frictional force between a magnetic head and the flexible magnetic disk directly influences the consumption electric power.
That is, a technique realizing securement of a soft and stable contact between the magnetic head and the flexible magnetic disk in a wide range from a low speed of revolution to a high-speed of revolution and realizing a head slider with a low frictional force and high reliability is regarded as an object for a next generation flexible magnetic disk.
For accomplishing such an object, the following can be considered.
1. Changing the speed of revolution of a flexible magnetic disk to be high by means of a magnetic head and a head slider to be used for an existing 3.5-inch floppy disk.
2. Using a magnetic head and a head slider to be used for a hard disk.
<AS FOR THE ITEM 1>
In a conventional so-called 3.5-inch floppy disk apparatus that performs record and reproduction at a speed of revolution of 300 rpm and has a capacity of 1.4 Mbytes, the load force of a head slider is about 20,000 mgf, and a frictional force to be produced reaches about 10,000 mgf. Accordingly, for scheming a change of the consumption electric power to be low, it is required to reduce the load force at first for reducing the frictional force.
On the other hand, if the number of revolution is increased for changing a transfer rate to be high though the head slider is urged to the flexible magnetic disk with such a high load force, a floating force is given to the head slider, and thereby the so-called magnetic spacing amount that is a space between the magnetic head and the flexible magnetic disk is increased. The phenomenon is considered to happen owing to an air film lubrication effect because a portion of the outer edge of the head slider beveled to a smooth curved surface called as “blend R” acts just similarly to a taper of a head slider for a floating type hard disk.
Because the increase of the magnetic spacing amount brings about a problem of the deterioration of an overwrite characteristic owing to the increase of a pulse width (PW 50), the lowering of an isolated reproduction wave output (IS TAA) and the lowering of the magnetic field strength, it becomes very hard to change the line density of the flexible magnetic disk to be high and to change the transfer rate of the flexible magnetic disk to be high.
If the magnetic head is made to contact the flexible magnetic disk with the load force simply increased for avoiding the problem, such a problem is produced in turn as dangerousness of lowering of reliability and durability owing to the abrasion of a magnetic head and the abrasion of the magnetic flexible disk at the time of the low speed of revolution of the disk. And then, even if the abrasion resistance of the flexible magnetic disk can be improved, a problem that the consumption electric power of the flexible magnetic disk apparatus is inevitably increased is produced.
<AS FOR THE ITEM 2>
Accordingly, various new flexible magnetic disk apparatuses recently enter the stage for avoiding those problems. Those apparatus employ the so-called floating type head slider having a taper flat structure that produces a positive pressure and further having a negative pressure structure similarly to that used for a hard disk. The floating type head slider can perform high-speed record and reproduction, with a stable low magnetic spacing amount of 40 nm-100 nm being kept without almost any contact to the flexible magnetic disk. The number of revolution of the flexible magnetic disk of the new flexible magnetic disk apparatus is about 3,000 rpm, the relative speed thereof is about 13.2 m/s, and the recording density thereof is about 100 Mbpi
2
-200 Mbpi
2
.
Now, for changing the recording density of such a flexible magnetic disk apparatus to be higher and for changing the transfer rate thereof to be higher, the magnetic spacing amount should be decreased to be 40 nm or less under a higher line speed.
However, the flatness of the flexible magnetic disk is inferior to that of the hard disk, the amount of the repeatable run-out (RRO) is several times to one digit as large as that of the hard disk. Furthermore, because the bending rigidity of the flexible magnetic disk is low, the flexible magnetic disk is sensitive to a deformation induced by external vibrations and non-repeatable run-out (NRRO) owing to vibrations. Consequently, it is difficult to keep the magnetic spacing amount between a magnetic head embedded in a slider rail and the flexible magnetic disk to a fixed value of 40 nm or less. As a result, a problem that the variation of signal outputs is large and the flexible magnetic disk apparatus becomes unstable is produced.
In addition, in this case, it is inevitable that the head slider frequently contacts the flexible magnetic disk. Then, abrasion powder of the flexible magnetic disk and the head produced by repeating partial contact between them attaches the head slider portion. Consequently, the stability of floating of the head slider is gradually damaged owing to the attached powder and the like. And then, the head slider itself begins to vibrate with the increment of pollution thereof. At last, a hard error occurs owing to head crush or an eternal damage of the flexible magnetic disk.
Besides, even if the slider rail is driven to run in a state of being completely contacted with the flexible magnetic disk for suppressing the aforesaid phenomena by means of the increment of the load force or the like, the abrasion of the flexible magnetic disk and the magnetic head becomes large because of a tendency that the contact pressure at a rear part of the head slider, which is a feature of the floating posture of the head slider, becomes very large. Thus, from this point of view, a problem that it is difficult to maintain the reliability for a long time occurs.
Furthermore, because the head slider does not float owing to the lost of the air film lubrication effect in a region of a small number of revolutions necessary for changing the consumption electric power to be low, a problem that the frictional force unexpectedly increases and the reliability cannot be maintained is produced.
As the aforementioned, the present situation of the performance of the flexible magnetic disk apparatus of the prior art is limited to a degree that the number of revolution of the flexible magnetic disk is about 3,000 rpm and an average recording surface density is about 200 Mbpi
2
.
SUMMARY OF THE INVENTION
Accordingly, the present invention concerns a slider of a magnetic head for performing record to and/or reproduction from a flexible magnetic disk made of a resin substrate on whic
Goto Kazuo
Kojima Naoto
Okazaki Yutaka
Ryoson Hiroyuki
Evans Jefferson
Frommer William S.
Frommer & Lawrence & Haug LLP
Ryan Matthew K.
Sony Corporation
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