Disk Drive Reader Writer Gap Measurement Using Disk-Locked Clock
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Solution Overview
Problem
Existing disk drive technologies face inefficiencies in head positioning and data recording due to the need for separate preamble and sync marks for servo sectors, which occupy additional recording space and can disrupt synchronization during read/write operations.
Innovation Solution
The implementation of a disk-locked clock system that measures and estimates the reader/writer gap in clock cycles, allowing for synchronous writing of extended servo data with each servo sector, thereby eliminating the need for preambles and sync marks and improving format efficiency by minimizing recording area usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate preamble and sync marks are used for servo sectors, then timing synchronization and head positioning are achieved, but recording space is consumed and format efficiency is reduced
Solution Approach 1:
The patent merges the preamble and sync mark functions into a single integrated servo sector structure. The servo sector begins directly with useful data without separate preamble and sync mark sections, eliminating redundant elements while maintaining timing synchronization through the disk-locked clock system that measures fractional clock cycles across the disk radius.
Solution Approach 2:
The patent extracts and eliminates the unnecessary preamble and sync mark sections from the servo sector structure. By removing these redundant elements, the recording space is freed up for actual data storage, directly reducing the recording area consumption while the disk-locked clock system maintains the necessary timing functions.
2Reliability
If preamble and sync marks are included in servo sectors, then proper gain adjustment and timing synchronization are enabled, but head positioning accuracy is reduced due to additional positioning steps
Solution Approach 1:
The patent removes the preamble and sync mark sections that cause additional positioning steps. The head positioning is streamlined by directly accessing data tracks without the need to first locate and synchronize through separate preamble and sync mark regions, thereby improving head positioning accuracy.
Solution Approach 2:
The patent performs timing synchronization in advance through the disk-locked clock system that measures fractional clock cycles at multiple radial locations. This preliminary timing setup eliminates the need for real-time preamble and sync mark processing during head positioning operations, improving positioning speed and accuracy.
3Productivity
If extended servo data is written synchronously with each servo sector, then format efficiency is improved and recording area is minimized, but measurement precision of reader/writer gap is required
Solution Approach 1:
The patent implements a feedback mechanism where the disk-locked clock system continuously measures fractional clock cycles at multiple radial locations and uses this information to accurately determine the reader/writer gap. This feedback loop enables precise gap measurement, which is then used to calculate the optimal synchronous write timing for extended servo data, achieving both high format efficiency and measurement precision.
Data Source
AI summary
A disk drive is disclosed comprising a disk, and a head actuated radially over the disk, wherein the head comprises a read element separated from a write element by a reader/writer gap. A disk-locked clock is synchronized to a rotation of the disk, wherein the disk-locked clock comprises a plurality of clock cycles, and the reader/writer gap spans a first number of the clock cycles comprising an integer of the clock cycles plus a fraction of one of the clock cycles. The fraction of one of the clock cycles is measured when the head is positioned at a first plurality of radial locations across the disk, and a second plurality of radial locations is estimated where the fraction substantially equals a full one of the clock cycles.