Interleaved Servo Patterns for Parallel HDD Self-Servo Writing
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Solution Overview
Problem
The self-servo writing process in data storage devices, particularly for hard disk drives, is lengthy and inefficient when writing servo tracks on multiple surfaces in parallel using multiple read/write heads, as existing HDD control circuitry lacks the capability to support simultaneous reading and writing, and specialized external control circuitry increases hardware costs.
Innovation Solution
Implementing control circuitry that supports parallel self-servo writing with interleaved servo patterns, allowing independent phase control for multiple read/write elements, using onboard hardware to write servo patterns on different storage medium surfaces with offset phases and tracks per inch values, and incorporating separate micro actuators for precise positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If specialized external control circuitry is added to support parallel self-servo writing, then productivity is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The existing HDD control circuitry is designed to perform multiple functions: it controls both traditional sequential self-servo writing and parallel self-servo writing operations. The circuitry uses the same read/write channels and control logic to write servo patterns to multiple disk surfaces simultaneously, eliminating the need for dedicated external control hardware and reducing overall system complexity while improving productivity
2Productivity
If specialized external control circuitry is added to support parallel self-servo writing, then productivity is improved, but manufacturing cost increases
Solution Approach 1:
The control circuitry within the HDD is designed to handle both sequential and parallel self-servo writing operations using the same hardware resources. By making the control circuitry universal rather than specialized, the patent avoids additional manufacturing costs while enabling parallel writing capability that improves productivity
3Manufacturing precision
If interleaved servo patterns with independent phase control are implemented, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The servo writing process is segmented into independent phase control for each read/write element. Each head can write servo patterns with independently controllable phase offsets, allowing precise alignment on multiple disk surfaces simultaneously. This segmentation of phase control enables high manufacturing precision while managing complexity through modular control of individual elements rather than centralized complex control
4Productivity
If multiple read/write heads write servo patterns in parallel, then productivity is improved, but reliability worsens due to phase control difficulties
Solution Approach 1:
By providing independent phase control for each read/write element, the system segments the phase control function, allowing each head to maintain reliable phase alignment independently while writing in parallel. This segmentation prevents phase control difficulties from affecting other heads, maintaining reliability while improving productivity
Solution Approach 2:
The system dynamically adjusts phase offset parameters for each read/write element during parallel self-servo writing. By changing the phase parameter independently for each head, the system maintains reliable servo pattern writing across multiple surfaces simultaneously, ensuring reliability while achieving high productivity
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 reduces data storage device production time and cost while enhancing efficiency and reliability by enabling simultaneous writing on multiple surfaces with improved phase control, supporting both self-servo writing and production read/write operations.
Implementation Method 1
writing a known pattern of magnetic transitions
Data Source
AI summary
Example control circuitry, data storage devices, and methods for parallel self-servo writing of interleaved servo patterns in a data storage device are described. The data storage device may include multiple heads actuated over different surfaces of a data storage device and receive read signals from two different heads over two different surfaces in parallel. The servo wedges of the two surfaces may be offset to enable independent determination of phase while writing servo patterns in parallel to the two surfaces using their respective heads.