HAMR Write Element Preheating for Thermal Equilibrium

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Solution Overview

Problem

Heat-assisted magnetic recording (HAMR) devices face challenges in achieving precise thermal equilibrium and maintaining consistent head-media spacing due to inefficiencies in optical transmission and thermal expansion, which affect data density and bit error rates.

Innovation Solution

Applying a preheat energizing current to the write element and driver circuitry before writing data, bringing them into thermal equilibrium, and using an energy source like a laser diode to heat the media, while controlling the write coil current to manage head-media spacing and minimize timing delays.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If optical transmission is used to heat the media in HAMR devices, then the media can be heated to enable magnetic recording, but thermal expansion and timing delays occur that affect data density and bit error rates

Engineering Contradiction:

Improvemedia temperatureVSAvoidtiming delays

Core Design Contradiction:

TemperatureVSLoss of time

Solution Approach 1:

The write element is pre-heated before the actual write operation to bring it into thermal equilibrium with the media. This preliminary heating action eliminates timing delays that would otherwise occur during the write process, ensuring consistent thermal conditions from the start of data recording.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent changes the temporal parameter of heating by applying it in advance (before writing) rather than during the write operation. This parameter change transforms the thermal state of the write element, bringing it into equilibrium with the media and eliminating the timing delays associated with thermal lag.

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If the write element is heated during the write operation, then data can be recorded on the media, but thermal equilibrium is not achieved leading to inconsistent recording conditions

Engineering Contradiction:

Improvedata recording precisionVSAvoidthermal equilibrium

Core Design Contradiction:

Manufacturing precisionVSStability of the object's composition

Solution Approach 1:

The write element undergoes preliminary heating before the write operation to achieve thermal equilibrium with the media. This advance preparation ensures that the write element maintains stable thermal conditions throughout the data recording process, improving recording precision.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The heating action continues before and during the write operation to maintain continuous thermal equilibrium. This uninterrupted heating ensures that the write element remains at the optimal temperature throughout the entire data recording process, preventing thermal fluctuations that would degrade recording precision.

Inventive Principle:

Principle #20Continuity of useful action

3Manufacturing precision

If the write coil current is increased to improve head-media spacing control, then spacing consistency improves, but power consumption increases

Engineering Contradiction:

Improvehead-media spacing consistencyVSAvoidwrite coil power consumption

Core Design Contradiction:

Manufacturing precisionVSUse of energy by moving object

Solution Approach 1:

The write coil is energized in advance to control head-media spacing before the actual write operation begins. This preliminary energizing establishes the optimal spacing early, allowing for reduced current during the write operation itself, thereby improving spacing consistency while managing power consumption.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The write coil current is applied periodically - first to control spacing, then to perform the write operation. This periodic application of current separates the spacing control function from the data writing function, optimizing both spacing consistency and power efficiency.

Inventive Principle:

Principle #19Periodic action

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 enhances thermal equilibrium, reduces timing delays, and maintains consistent head-media spacing, improving data density and bit error rates in HAMR devices.

Implementation Method 1

An energy source configured to heat the portion of the medium being magnetized by the write element

Methodology Applied

Scientific EffectLaser heating: Laser

Implementation Method 2

A preheat energizing current is applied to the write element during an interval before writing the data to the portion of the medium... brings at least one of the write element and driver circuitry into thermal equilibrium

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 3

The write element applies a magnetic field to the medium in response to an energizing current

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS9019646B2Heat assisted magnetic recording device with pre-heated write element

Publication Date: 2015.04.28 SEAGATE TECH LLC

AI summary

An apparatus includes a write element configured to apply a magnetic field to write data on a portion of a heat-assisted magnetic recording media in response to an energizing current. An energy source is configured to heat the portion of the media being magnetized by the write element. A preheat energizing current is applied to the write element during an interval before writing the data to the portion of the media. The preheat energizing current does not cause data to be written to the media and brings at least one of the write element and driver circuitry into thermal equilibrium prior to writing the data on the portion.