Hard Disk Drive Head Positioning Feedback Control

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Solution Overview

Problem

The challenge in hard disk drives is to increase areal recording density while maintaining accurate head positioning, as distortions in track shapes due to spindle motor deflection and airflow disturbances lead to repeatable runout errors, limiting the number of servo areas and reducing linear density.

Innovation Solution

A hard disk drive system that includes a positioning module to adjust the read head based on output from adjacent servo areas, allowing for real-time correction of head displacement during data write, thereby increasing track density without risking data overwrite in adjacent tracks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the number of servo areas is increased to improve positioning accuracy, then head positioning accuracy is improved, but data area is reduced and linear density decreases

Engineering Contradiction:

Improvepositioning accuracyVSAvoidlinear density

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The patent uses feedback from read head output during data writing to detect head displacement and applies real-time correction to the write head position, enabling accurate positioning with fewer servo areas

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces mechanical positioning reliance on frequent servo areas with an electronic/digital correction system that uses feedback signals and calculations to compensate for track deviations

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If track width is reduced to increase track density, then areal recording density is improved, but positioning accuracy deteriorates and data overwrite risk increases

Engineering Contradiction:

Improvetrack densityVSAvoidpositioning accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The system continuously monitors head position during data writing using feedback from the read head and applies real-time corrections, enabling safe operation with narrower tracks that would otherwise risk data overwrite

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent dynamically adjusts write head position based on real-time feedback parameters, allowing the system to maintain precise positioning control even when track width is reduced to increase track density

Inventive Principle:

Principle #35Parameter changes

3Productivity

If track width is reduced to increase track density, then areal recording density is improved, but data overwrite risk increases

Engineering Contradiction:

Improveareal recording densityVSAvoiddata overwrite risk

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The feedback mechanism detects head displacement during writing and triggers corrections before data overwrite can occur, enabling safer operation at higher track densities

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system takes preliminary corrective action by adjusting head position based on detected displacement trends before actual data overwrite can happen, preventing reliability issues

Inventive Principle:

Principle #9Preliminary anti-action

Data Source

PatentUS10020017B2Hard disk drive and head positioning method

Publication Date: 2018.07.10 KK TOSHIBA

AI summary

According to one embodiment, a hard disk drive includes a disk including a plurality of data areas, and a plurality of servo areas between the plurality of data areas, an arm holding a write head and a read arm, and a positioning module which positions the read head or the write head by rotating the arm, wherein the positioning module positioning the write head by positioning the read head, and adjusting a position of the read head or the write head, based on an output of the read head located in a data area between two servo areas adjacent in a peripheral direction, of the plurality of servo areas.