Thin Film Magnetic Head Contact Detection via Stabilized Domains

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Solution Overview

Problem

The increasing recording density in magnetic disks requires a more accurate control of the floating height of thin film magnetic heads to prevent contact with the disk surface, which current technologies struggle to achieve, leading to issues like abnormal signals and head abrasion.

Innovation Solution

Incorporating a contact detection section with a magnetic material layer and an antiferromagnetic material layer as a magnetic-domain stabilizing structure, which suppresses temporal variations in the magnetic domain structure due to disturbance magnetic fields, allowing for precise detection of contact and control of the floating height.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the magnetic spacing is reduced to compensate for deterioration of recording and reproducing functions, then the signal recording ability and signal magnetic field intensity are improved, but the thin film magnetic head contacts the disk surface causing abnormal signals and head abrasion

Engineering Contradiction:

Improvesignal recording abilityVSAvoidcontact between head and disk

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The contact detection section continuously monitors the magnetic head's position relative to the disk surface and provides feedback signals to the control section. When contact or near-contact is detected, the control section adjusts the magnetic spacing dynamically, creating a closed-loop control system that prevents head-disk contact while maintaining optimal recording and reproducing performance.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces mechanical contact detection methods with a magnetic field-based detection system. The contact detection section uses magnetic sensing elements to detect the magnetic head's position and contact status without mechanical interaction, enabling precise control while avoiding mechanical wear and abnormal signals.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Length of moving object

If the floating height of the magnetic head slider is reduced, then the magnetic spacing is minimized for better signal quality, but control precision is insufficient leading to contact with disk surface

Engineering Contradiction:

Improvemagnetic spacingVSAvoidcontrol precision of floating height

Core Design Contradiction:

Length of moving objectVSMeasurement precision

Solution Approach 1:

The contact detection section provides real-time feedback on the magnetic head's floating height and contact status to the control section. This feedback enables precise control of the magnetic spacing by dynamically adjusting the head position based on actual detection results, achieving both minimal magnetic spacing and high control precision.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The contact detection section acts as an intermediary between the magnetic head slider and the control system. It translates the physical state of the floating height and contact conditions into detectable signals, enabling precise control of the magnetic spacing without direct mechanical intervention.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Measurement precision

If a heating means is provided to protrude the magnetic conversion element toward the ABS side, then the magnetic spacing is achieved with high accuracy, but the device complexity increases

Engineering Contradiction:

Improvemagnetic spacing control accuracyVSAvoidstructure of magnetic head

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The contact detection section monitors the magnetic head's position and provides feedback to the control section, which adjusts the heating element's activation accordingly. This feedback-based control enables precise magnetic spacing control while using the heating element only when necessary, reducing overall device complexity compared to continuous heating mechanisms.

Inventive Principle:

Principle #23Feedback

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This configuration enables high-accuracy detection of contact between the thin film magnetic head and the disk, stabilizing the magnetic domain structure and enhancing the control of the floating height, thereby reducing noise and increasing the lifespan of the magnetic head.

Implementation Method 1

a magnetic-domain stabilizing structure stabilizing a magnetic domain structure of the magnetic material layer

Methodology Applied

Scientific EffectMagnetic domain structure stabilization: Magnetism

Data Source

PatentUS9852755B2Thin film magnetic head, head gimbals assembly, head arm assembly, and magnetic disk unit

Publication Date: 2017.12.26 TDK CORP

AI summary

This thin film magnetic head includes a magnetic pole including an end surface exposed on an air bearing surface, and a contact detection section including a magnetic material layer provided near the air bearing surface, and a magnetic-domain stabilizing structure stabilizing a magnetic domain structure of the magnetic material layer.