Shield biasing for mr devices
a shield biasing and magnetic storage technology, applied in the field of magnetic storage systems, can solve the problems of adverse tribological effects, adverse tribological effects, and adverse effects on the head of the magnetic head, and achieve the effects of reducing the number of magnetic heads
Inactive Publication Date: 2008-10-23
INT BUSINESS MASCH CORP
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Problems solved by technology
In any of the above-mentioned types of heads, e.g., AMR, GMR, MTJ, etc., several forces are present, each potentially contributing to adverse effects on the head.
These high fields are associated with adverse tribological effects, including electrostatic debris deposition and pitting of the head insulator due to electric discharges.
Due to the varying voltage differentials and irregular electric fields between the various parts of a head as well as between head and tape, magnetic heads tend to suffer from adverse tribological interactions, which include electrical discharge, tape changes, head erosion, debris buildup, chemical conversion, head sensor shorting, etc.
Such voltages are strongly implicated in unfavorable tribological processes such as electrochemical reactions, electrostatic accumulation of debris, and even certain types of wear.
The voltage differences between the adjacent reader shield and substrate is problematic due to their close proximity, and is compounded by the potentially large localized electric fields created by a conductive substrate, e.g., of AlTiC.
Several solutions have been contemplated, but each of these have drawbacks.
However, if the reader shields are not clamped to ground, the voltage differential leads to the aforementioned tribological effects between the shields and substrate.
Grounding the shields in a multi-sensor head is generally impractical.
Even if the shields are grounded, adverse tribological effects may occur depending on the tape electrical and mechanical characteristics and other aspects of the tape path, such as ground or floating of guides.
Another problem encountered is that the readers are susceptible to shield-shorting which may occur in combination with substrate shorting, as a result of running magnetic is recording tape having insufficient lubricity across the head at very low humidity, which in turn is found to produce accumulations of conductive material on the MR element, shields and substrate.
Shorting is a well-known cause of reading errors.
For instance, forcibly recessing the sensor so that its components do not develop the conductive accumulation is difficult to manufacture, and also generally produces undesirable spacing loss for the data readers, which must read much higher frequencies than the servo readers.
Also, attempting to set shield potentials by tuning the MR bias could result in unacceptable bias values.
Method used
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[0030]The following description is the best mode presently contemplated for carrying out the present invention. This description is made for the purpose of illustrating the general principles of the present invention and is not meant to limit the inventive concepts claimed herein. Further, particular features described herein can be used in combination with other described features in each of the various possible combinations and permutations.
[0031]In the drawings, like and equivalent elements are numbered the same throughout the various figures.
[0032]The present invention includes a system for setting the potentials of some or all the MR reader shields, which are assumed to be connected to the MR leads via a charge clamp, to some predetermined potential, preferably that of the wafer substrate and closure, in a manner that is not affected by the bias currents in the readers. Setting the shields to precisely the substrate potential is desirable for reducing or eliminating the surface...
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Abstract
A magnetic data system according to one embodiment includes a head having a plurality of readers formed above a common substrate, each reader further comprising a shield and a sensor, a bias circuit associated with each reader for passing a bias current through the sensor thereof, wherein the bias circuits are floating. A charge clamp electrically couples each shield to the associated bias circuit. A shield biasing circuit is operatively coupled to each shield for setting a potential of the shield independently of the bias current.
Description
RELATED APPLICATIONS[0001]This application is a continuation of U.S. patent application Ser. No. 11 / 304,496, filed Dec. 14, 2005, and which is herein incorporated by reference.FIELD OF THE INVENTION[0002]The present invention relates to magnetic storage systems, and more particularly, this invention relates to a magnetic storage system having reader shields at definable potentials.BACKGROUND OF THE INVENTION[0003]Business, science and entertainment applications depend upon computers to process and record data, often with large volumes of the data being stored or transferred to nonvolatile storage media, such as magnetic discs, magnetic tape cartridges, optical disk cartridges, floppy diskettes, or floptical diskettes. Typically, magnetic tape is the most economical means of storing or archiving the data. Storage technology is continually pushed to increase storage capacity and storage reliability. Improvement in data storage densities in magnetic storage media, for example, has resu...
Claims
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IPC IPC(8): G11B5/33
CPCG11B5/3912G11B2005/0016
InventorBISKEBORN, ROBERT GLENN
OwnerINT BUSINESS MASCH CORP