Dynamic magnetic information storage or retrieval – Fluid bearing head support – Disk record
Reexamination Certificate
1998-10-23
2001-01-23
Evans, Jefferson (Department: 2754)
Dynamic magnetic information storage or retrieval
Fluid bearing head support
Disk record
C360S237000, C360S237100
Reexamination Certificate
active
06178068
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a magnetic head employed in a magnetic disk drive such as a hard disk drive (HDD). In particularly, the invention relates to a quasi contact head comprising a slider with a flying surface opposed to a magnetic disk, and a composite layer formed on the slider at its trailing end so as to contain a head element, wherein an edge of the slider or composite layer first approaching the magnetic disk is subjected to grinding by an initial abrasion with the magnetic disk.
2. Description of the Prior Art
The ongoing demand to improve the recording density of information recorded on a magnetic disk makes it necessary drive to reduce the magnetic space between a reading/writing gap of a magnetic head element and a magnetic disk. Reduction in the magnetic space must be achieved without causing actual contact between the slider and the magnetic disk in a conventional flying magnetic head generally used. Probability of physical contact between the slider and the magnetic disk is accordingly minimized, possibly to zero, by taking account of any factors varying the flying height of the slider over the surface of the magnetic disk. However, reduction in such probability tends to cause an increase in the flying height of the slider.
On the other hand, a quasi contact head is supposed to reduce the magnetic space between a reading/writing gap and a magnetic disk as compared with the above-mentioned conventional flying magnetic head, since the flying height of the slider can be determined on the assumption that the slider contacts the magnetic disk.
When a quasi contact head employs a magnetoresistance (MR) element, the gap of the MR element is in some cases supposed to collide with a tiny protrusion caused by surface roughness of the magnetic disk. The contact may cause a momentary temperature rise in the gap, namely, a thermal asperity, to thereby bring about a large change in the magnitude of magnetoresistance detected by the MR element. As a result, it is very difficult to allow the MR element to achieve a precise reading operation in the quasi contact head.
SUMMARY OF THE INVENITON
It is accordingly an object of the present invention to provide a quasi contact head capable of allowing a magnetic head element to approach a magnetic disk without causing collision of the magnetic head element with the magnetic disk.
According to a first aspect of the present invention, there is provided a quasi contact head comprising: a slider with a flying surface opposed to a magnetic disk; a composite layer formed on the slider at its trailing end so as to contain a head element; an exposure surface formed on the composite layer so as to expose the head element; a step retracting the exposure surface from the flying surface; and an edge formed between the step and the flying surface, to be subjected to grinding.
In addition, according to a second aspect of the present invention, there is provided a magnetic disk drive comprising: a magnetic disk; a slider with a flying surface opposed to the magnetic disk; a composite layer formed on the slider at its trailing end so as to contain a head element; an exposure surface formed on the composite layer so as to expose the head element; and a step retracting the exposure surface from the flying surface; wherein an intersection between a first plane including the flying surface and a second plane including the step projects within the magnetic disk during rotation of the magnetic disk.
A magnetic disk drive employing the quasi contact head of the first aspect, or a magnetic disk drive of the second aspect, enables determination of the flying height for the slider in consideration of the edge wearing off by the abrasion. As a result, an additional flying height or a flying margin can be reduced to the utmost so as to suppress the flying height of the slider at the lower level. When the edge wears off by the abrasion with the magnetic disk, the magnetic space between the head element to the magnetic disk can be defined by a distance between the worn edge and the exposure surface.
Moreover, the head element can approach the surface of the magnetic disk as much as possible without interference with the magnetic disk since the exposure surface retreats from the flying surface. The term “interference” can be defined as contact or collision of the head element with a tiny protrusion caused by surface roughness of the magnetic disk.
In any of the above-mentioned inventions, the composite layer may contain a magnetoresistance element having a gap appearing on the exposure surface. Formation of the step serves to avoid interference between the head element and the surface of the magnetic disk, so that a momentary temperature rise by collision or a thermal asperity can be prevented in the magnetoresistance element. Information can reliably be read out of the magnetic disk in a precise manner. Therefore, a quasi contact head can employ a magnetoresistance element which is sensitive to variation in temperature.
The edge may be subjected to a def lashing process. The deflashing process serves to eliminate flash formed at production of the slider, so that it is possible to avoid generation of scars on the surface of the magnetic disk and generation of scattering particles from the worn slider at the initial abrasion.
The slider is preferably subjected to a spring load equal to or less than 0.5 gf in a direction toward the magnetic disk. If the spring load is heavier, the edge may excessively wear off when the edge contacts the magnetic disk during rotation of the magnetic disk. In addition, if the spring load is equal to or less than 0.5 gf, the slider hardly wears off while the slider transits from the seated position on the surface of the magnetic disk to the flying position over the surface of the disk.
The slider may be supported on a tip end of a leaf spring with a vibration suppression component for absorbing vibration of the leaf spring. The vibration suppression component may serve to stabilize the attitude of the slider, so that it is possible to suppress variation in the magnetic space to the utmost.
A method of producing the above-mentioned quasi contact head, which comprises a composite layer to contain a head element and an exposure surface retreating from the flying surface for exposing the head element, may comprise allowing the edge between the flying surface and the step to wear off by grinding at the initial abrasion with the magnetic disk. Grinding at the initial abrasion with the magnetic disk can be achieved at a factory.
It should be noted that the edge is formed on either of the slider and the composite layer. If the edge is formed on the composite layer, the magnetic disk can be prevented to the utmost from damaging by collision with the edge since the composite layer is in general made of material softer than that of the slider.
The present invention can be applied not only to the aforementioned magnetic disk drive, but also to any kind of information recording apparatus employing a flying head in general.
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Evans Jefferson
Fujitsu Limited
Greer Burns & Crain Ltd
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