Laser Power Control for Thermal Management in Data Storage

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Solution Overview

Problem

Existing data storage devices face issues with abrupt changes in laser power after write operations, which can lead to material buildup on the head, affecting fly height and performance during read/write operations, and potentially damaging the head or corrupting data.

Innovation Solution

Gradually decreasing the laser power after a write operation using a controlled decrease function to prevent material buildup on the disk surface, spreading it over multiple servo sectors, and employing a 'burn-off' power to correct marginal data sectors, thereby maintaining data integrity and extending the life of the head components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If laser power is abruptly decreased to off state after write operation, then energy consumption is reduced, but material buildup occurs on the head affecting fly height and performance

Engineering Contradiction:

Improvelaser energy consumptionVSAvoidhead performance and data integrity

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The patent applies preliminary action by gradually decreasing laser power before completely turning it off after a write operation. This controlled reduction prevents material buildup on the head by allowing the laser to continue operating at low power levels for a transition period, thereby maintaining head performance and data integrity while still reducing energy consumption compared to abrupt shutdown.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements beforehand cushioning by introducing a gradual power decrease phase that acts as a buffer between full power write mode and complete shutdown. This cushioning period prevents the harmful effect of material buildup by maintaining minimal laser operation, thus protecting head performance while achieving energy savings.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Reliability

If laser power is gradually decreased after write operation, then material buildup is prevented on the head, but energy consumption increases compared to abrupt shutdown

Engineering Contradiction:

Improvehead performance and data integrityVSAvoidlaser energy consumption

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent applies partial action by using a gradual power decrease rather than complete shutdown immediately after writing. The laser operates at progressively reducing power levels for a defined period, providing just enough energy to prevent material buildup without the full energy consumption of continuous operation, thus achieving a balance between reliability and energy efficiency.

Inventive Principle:

Principle #16Partial or excessive action

3Productivity

If high laser power is applied continuously, then write operations are performed efficiently, but material buildup damages the head and corrupts data

Engineering Contradiction:

Improvewrite operation efficiencyVSAvoidmaterial buildup damage

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent implements periodic action by transitioning the laser from continuous high power during write operations to a gradual power decrease phase afterward. This periodic modulation of power levels allows efficient writing when needed while preventing material buildup through controlled power reduction, thus maintaining productivity while eliminating harmful effects.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent applies parameter changes by dynamically adjusting the laser power parameter from high levels during writing to gradually decreasing levels afterward. This parameter transformation allows the system to achieve efficient write operations at high power while preventing material buildup through controlled parameter reduction in the post-write phase.

Inventive Principle:

Principle #35Parameter changes

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 prevents damage to the head, maintains data integrity, and extends the life of the disk drive by evenly distributing material buildup and correcting marginal data sectors, ensuring consistent performance and reliability.

Implementation Method 1

the head comprises a laser configured to heat the disk while writing data to the disk

Methodology Applied

Scientific EffectLaser heating: Heating

Implementation Method 2

the laser power is gradually decreased to an off state based on a decrease function

Methodology Applied

Scientific EffectThermal cooling: Cooling

Data Source

PatentUS9922676B1Data storage device gradually decreasing laser power after write operation

Publication Date: 2018.03.20 WESTERN DIGITAL TECHNOLOGIES INC

AI summary

A data storage device is disclosed comprising a head actuated over a disk, wherein the head comprises a laser configured to heat the disk while writing data to the disk. A write power is applied to the laser in order to write data to the disk during a write operation. A determination is made as to whether the laser power should be in an off state after the write operation. After the write operation, the laser power is gradually decreased to the off state based on a first decrease function.