Servo Zone Transition Optimization for Hard Disk Drives

Solution Overview

Problem

Existing storage systems face challenges in accurately positioning read/write heads on hard disk drives due to eccentricity between servo tracks and the axis of rotation, leading to increased sector error rates and reduced head yield, especially when using pre-written or post-written servo patterns.

Innovation Solution

The implementation of servo zone transition optimization methods, which involve assessing the read/write head operations and formatting the disk surface with variable servo density zones and overlap regions to adjust servo sector error rates and zone transitions, allowing for improved servo performance and head yield by changing servo density at zone boundaries.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If pre-written or post-written servo patterns are used, then manufacturing efficiency is improved, but sector error rates increase due to eccentricity between servo tracks and axis of rotation

Engineering Contradiction:

Improvemanufacturing efficiencyVSAvoidsector error rate

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies local quality by creating overlap regions at zone boundaries where servo patterns from adjacent zones overlap. This local modification allows the system to compensate for eccentricity-induced positioning errors specifically at transition points without changing the entire servo pattern structure, thereby maintaining manufacturing efficiency while reducing sector error rates.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent implements preliminary action by pre-formatting overlap regions with servo patterns from both adjacent zones before actual data recording. This advance preparation ensures that when the read/write head transitions between zones, it has already encountered the appropriate servo patterns, reducing positioning errors and sector error rates from the outset.

Inventive Principle:

Principle #10Preliminary action

2Quantity of substance

If servo zone transitions are implemented, then recording density is improved, but head yield decreases due to positioning errors at zone boundaries

Engineering Contradiction:

Improverecording densityVSAvoidhead yield

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent applies local quality by creating overlap regions at zone boundaries where servo patterns from adjacent zones overlap. This local modification allows the system to compensate for eccentricity-induced positioning errors specifically at transition points without changing the entire servo pattern structure, thereby maintaining manufacturing efficiency while reducing sector error rates.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent implements preliminary action by pre-formatting overlap regions with servo patterns from both adjacent zones before actual data recording. This advance preparation ensures that when the read/write head transitions between zones, it has already encountered the appropriate servo patterns, reducing positioning errors and sector error rates from the outset.

Inventive Principle:

Principle #10Preliminary action

3Quantity of substance

If variable servo density zones are used, then recording capacity is improved, but servo performance deteriorates at zone boundaries due to eccentricity

Engineering Contradiction:

Improverecording capacityVSAvoidservo performance

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent applies local quality by creating overlap regions at zone boundaries where servo patterns from adjacent zones overlap. This local modification allows the system to compensate for eccentricity-induced positioning errors specifically at transition points without changing the entire servo pattern structure, thereby maintaining manufacturing efficiency while reducing sector error rates.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent implements preliminary action by pre-formatting overlap regions with servo patterns from both adjacent zones before actual data recording. This advance preparation ensures that when the read/write head transitions between zones, it has already encountered the appropriate servo patterns, reducing positioning errors and sector error rates from the outset.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS10777224B2Servo zone transition optimization for disk drives

Publication Date: 2020.09.15 SEAGATE TECH LLC

AI summary

Systems and methods for servo zone transition optimization are described. In one embodiment, the storage system device includes a disk drive and a controller. In some embodiments, the controller may be configured to assess at least one operation of a read/write head of the disk drive; and format, based at least in part on the assessing of the read/write head, a disk surface of the disk drive with a first servo zone, a second servo zone, and an overlap region extending between a start point of the second servo zone and an end point of the first servo zone. In some cases, the overlap region starts towards a disk inner diameter (ID) and ends towards a disk outer diameter (OD).