Dynamic magnetic information storage or retrieval – Automatic control of a recorder mechanism – Controlling the head
Reexamination Certificate
1999-02-24
2003-03-04
Sniezek, Andrew L. (Department: 2651)
Dynamic magnetic information storage or retrieval
Automatic control of a recorder mechanism
Controlling the head
C360S031000
Reexamination Certificate
active
06529342
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to a magnetic head for reading or writing data to or from a magnetic medium, and more particularly, to a method for controlling the flying height between the head and the medium.
Computers typically include a magnetic storage device such as a disk drive. The disk drive may include a magnetic storage medium, such as a magnetic disk, on which data can be recorded or reproduced. Data may be recorded or reproduced on radially spaced data tracks on a surface of the disk. A magnetic head supported by a slider includes a transducer that is positioned over a data track to read data from or write data to the track on the disk surface. The slider also includes an air bearing surface formed on the surface of the slider that opposes the disk surface.
One technique for reading and writing information from the data track includes contact start and stop (“CSS”) recording. In CSS recording, the magnetic head rests on an inner portion of the disk surface when the disk is stationary. When the disk rotates, an aerodynamic force is generated between the disk surface and the air bearing surface that causes the head to “fly” over the disk surface. A gap in thus formed between the disk surface and the magnetic head. The height at which the head travels over the disk is typically referred to as the “flying height.”
The flying height may be used to determine the recording density or capacity of a data storage system. Lowering the flying height of the head relative to the disk surface may result in higher recording densities. However, as the flying height is reduced, contact between the head and disk increases. This may cause increased damage or wear to the head or disk. Smooth disk surfaces are typically used to minimize the contact between the head and disk due to reduced flying height. However, the head may stick to the surface of the disk, if the roughness of the disk is too small. This may result in disk driven failure, head-disk crash, or loss of recorded data.
One known technique to solve the sticking problem is to form a “texture” pattern on the surface of the disk. This up-and-down wavy pattern changes the surface shape so as to increase the surface roughness. The pattern of the surface texture reduces the contact between the head and disk. Thus, the sticking is reduced.
Certain drawbacks exist with the above configuration. Abrasion may occur between the head and disk. As a result, the head and disk may suffer damage from fine powders generated by the abrasion. Additionally, medium noises due to the surface texture may be generated in the recording frequency domain of the disk, and thus increase the error rate during data reproducing. Also, the head still tends to contact the disk surface, where the slope of the surface texture rises.
Therefore, a need exists for a method for controlling the flying height of a magnetic head that reduces damage to the head during data reproduction or recording as well as increases the data density in a data storage system.
SUMMARY OF THE INVENTION
In general, the present invention is directed to a method for controlling the flying height of a data storage system. The head may be vertically displaced relative to a storage medium in the data storage system by applying a voltage to an interface between the head and the storage medium.
Accordingly, in one aspect, the invention is directed to a method for controlling a magnetic head spaced from a magnetic storage medium. The method.includes forming a dielectric layer on the storage medium, and applying a voltage to an interface between the storage medium and the head to vertically displace the head relative to the storage medium.
Implementations of the invention include one or more of the following. The applied voltage may be an AC or DC voltage. The magnetic head, the storage medium, and the dielectric layer may be modeled as a variable capacitor. The head may be vertically displaced relative to the storage medium to increase the data density between the head and the medium. The head may be controlled to fly at a constant or variable distance relative to a surface of the medium.
In another aspect, the invention is directed to a data storage system that includes a magnetic storage medium. A magnetic head is positioned relative to the storage medium, and a voltage source is electrically coupled to the head to supply a voltage to an interface between the head and the medium to vertically move the head relative to the medium.
The head may include a slider and an air bearing surface formed on a surface of the slider. A transducer assembly may be formed proximate the air bearing surface to read or write data to or from a plurality of tracks on the storage medium.
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Feng Zhu
Gubbi Vidyadhara K.
Poon Chiu-Shing F.
Shih Chung Y.
Fish & Richardson P.C.
Seagate Technology Inc.
Sniezek Andrew L.
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