Magnetic Head Clearance Control via Electromagnet Force

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Solution Overview

Problem

Magnetic hard disk drives face challenges in maintaining consistent clearance between the transducer and the magnetic disk due to system disturbances, leading to potential read/write errors and limitations in areal density, particularly in heat-assisted magnetic recording (HAMR) media where thermal expansions complicate precise spacing adjustments.

Innovation Solution

The use of an electromagnet in the magnetic head to generate a magnetic force that adjusts the clearance between the head and the magnetic recording medium, allowing for fine control of spacing without risking data erasure, by leveraging the high coercivity of HAMR media to apply an attractive force sufficient for adjustment while minimizing domain noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a heater is used to adjust clearance through thermal expansion, then clearance adjustment is achieved, but power consumption increases and operating temperature rises

Engineering Contradiction:

Improveclearance adjustment precisionVSAvoidpower requirement for heater control

Core Design Contradiction:

Manufacturing precisionVSUse of energy by moving object

Solution Approach 1:

The patent replaces the thermal expansion mechanism with a magnetic force mechanism. An electromagnet generates a magnetic field that exerts an attractive force on the magnetic recording medium, directly adjusting the clearance between the transducer and medium without requiring thermal expansion. This substitution eliminates the need for high-power heating elements while achieving the same clearance control function.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the physical parameter used for clearance adjustment from temperature (thermal expansion) to magnetic field strength (electromagnetic force). By controlling the current through the electromagnet, the magnetic force can be precisely adjusted to achieve the desired clearance, providing a more energy-efficient alternative to thermal control.

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If thermal expansion is used for clearance adjustment, then spacing control is achieved, but operating temperature increases causing potential damage

Engineering Contradiction:

Improvespacing controlVSAvoidoperating temperature

Core Design Contradiction:

Manufacturing precisionVSTemperature

Solution Approach 1:

The patent substitutes the thermal expansion system with an electromagnetic force system. The electromagnet generates an attractive force that directly controls the spacing between the transducer and recording medium, eliminating the need to raise operating temperatures and avoiding thermal damage to sensitive components.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Manufacturing precision

If magnetic force is applied to adjust clearance, then precise spacing control is achieved, but data erasure risk increases on conventional media

Engineering Contradiction:

Improveclearance adjustment precisionVSAvoiddata erasure risk

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent applies magnetic force locally and selectively to adjust clearance only in the region where the electromagnet is positioned, rather than applying a strong magnetic field across the entire disk surface. This localized application allows precise clearance control while minimizing the risk of erasing data on conventional magnetic media.

Inventive Principle:

Principle #3Local quality

4Manufacturing precision

If heater control is used for clearance adjustment, then spacing control is achieved, but system complexity increases

Engineering Contradiction:

Improveclearance controlVSAvoidheater control system complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent replaces the complex thermal control system with a simpler electromagnetic control system. The electromagnet can be directly controlled by adjusting the current, providing a more straightforward and responsive control mechanism compared to thermal systems that require heat management, thermal mass considerations, and slower response times.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 approach reduces the power requirement for heater control, lowers operating temperatures, and enhances the reliability of the read/write head by allowing precise clearance adjustments, thereby improving areal density and reducing potential noise in the magnetic medium.

Implementation Method 1

A current is applied to an electromagnet of the magnetic head. The current induces a magnetic force between the magnetic head and the magnetic recording medium that adjusts a clearance therebetween.

Methodology Applied

Scientific EffectElectromagnetic force: Electromagnet

Implementation Method 2

The current induces a magnetic force between the magnetic head and the magnetic recording medium that adjusts a clearance therebetween

Methodology Applied

Scientific EffectMagnetic force: Magnetic Field

Data Source

PatentUS9202497B2Adjusting a clearance between a magnetic head and a magnetic recording medium using a magnetic force

Publication Date: 2015.12.01 SEAGATE TECH LLC

AI summary

A media-facing surface of a magnetic head is positioned proximate a moving magnetic recording medium. A current is applied to an electromagnet of the magnetic head. The current induces a magnetic force between the magnetic head and the magnetic recording medium that adjusts a clearance therebetween.