Substrate biasing for mr devices

Abstract

A magnetic data system according to one embodiment includes at least, one reader formed above a substrate, the at least one reader further comprising a shield and a magnetoresistive (MR) sensor. A first circuit sets a voltage (Vsub) of the substrate to about a voltage (Vshield) of the shield of the at least one reader.

Description

RELATED APPLICATIONS[0001]This application is a continuation of U.S. patent application Ser. No. 11 / 304,440 filed Dec. 14, 2005, which is incorporated by reference.FIELD OF THE INVENTION[0002]The present invention relates to magnetoresistive (MR) devices, and more particularly, this invention relates to an MR device having an electrically biased substrate.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 resulted from improved medium...

AI Technical Summary

Benefits of technology

The patent describes a magnetic data system that includes a reader with a shield and a magnetoresistive (MR) sensor. The system uses a first circuit to set the voltage of the substrate to a level that matches the shield, reducing wear and corrosion and minimizing the risk of electrical discharge. The system also includes multiple readers with shields and MR sensors, and second circuits to set the voltage of the shield to match the MR sensor of each reader. A bias circuit is used to pass an MR bias current through the MR sensor, and a mechanism adjusts the voltage of the shield to match the voltage of the associated MR sensor. The system can be used in a tape drive system, which includes a magnetic head, a drive mechanism, and a controller. The technical effects of the invention include reducing friction and wear, minimizing corrosion, and reducing the risk of electrical discharge.

Problems solved by technology

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 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.

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