In-drive servo spiral writing using coarse guide reference
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Solution Overview
Problem
The existing methods for writing servo spirals on hard disk drives require external equipment, which is time-consuming and expensive in high-volume manufacturing, and rely on precise timing or specialized hardware, making them impractical for accurate in-drive spiral writing.
Innovation Solution
A position-based scheme is employed to launch servo spirals from pre-existing coarse guide spirals, allowing the write head to move to different radial locations for writing fine reference spirals, eliminating the need for high-accuracy timing devices and specialized hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If external equipment (media writer or servo writing machine) is used to write servo spirals, then manufacturing precision of servo spiral positioning is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The HDD performs self-servo-writing by using its own actuator and read/write heads to write servo spirals and position information, eliminating the need for external media writers or servo writing machines. The system leverages its inherent components to accomplish the servo pattern writing task.
Solution Approach 2:
Coarse guide spirals are written first as intermediary structures that serve as reference paths for launching fine servo spirals. These coarse spirals act as a mediator between the actuator mechanism and the final servo patterns, enabling accurate positioning without external equipment.
2Manufacturing precision
If precise timing devices are used to launch servo spirals at accurate positions, then manufacturing precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces complex timing-based control systems with a geometry-based approach. Instead of using precise timing devices to determine when to launch each servo spiral, the system uses the physical geometry of coarse guide spirals and radial position calculations to determine launch points, substituting mechanical/timing complexity with geometric computation.
Solution Approach 2:
The patent transitions from a one-dimensional timing-based launch mechanism to a two-dimensional spatial approach by utilizing radial positions and angular calculations. Launch points are determined by coordinates (radial distance from disk center and angular position) rather than temporal sequences, adding a spatial dimension to the control mechanism.
3Manufacturing precision
If external equipment is used for servo spiral writing, then manufacturing precision is improved, but productivity decreases due to time-consuming processes
Solution Approach 1:
The HDD performs self-servo-writing by using its own actuator and read/write heads to write servo spirals and position information, eliminating the need for external media writers or servo writing machines. The system leverages its inherent components to accomplish the servo pattern writing task.
Solution Approach 2:
Coarse guide spirals are written first as preliminary structures that establish reference paths for subsequent fine servo spiral writing. This preliminary action creates a foundation that guides the more precise servo patterns, enabling accurate positioning without requiring external equipment during the final servo writing stage.
4Manufacturing precision
If specialized hardware is used to achieve accurate launch points, then manufacturing precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent replaces complex timing-based control systems with a geometry-based approach. Instead of using precise timing devices to determine when to launch each servo spiral, the system uses the physical geometry of coarse guide spirals and radial position calculations to determine launch points, substituting mechanical/timing complexity with geometric computation.
Solution Approach 2:
Coarse guide spirals are written first as intermediary structures that serve as reference paths for launching fine servo spirals. These coarse spirals act as a mediator between the actuator mechanism and the final servo patterns, enabling accurate positioning without external equipment.
Data Source
AI summary
A reference spiral is written on a recording surface of a hard disk drive. By launching writing of fine guide spirals from a launch point that is disposed on a pre-existing coarse guide spiral, writing of the fine guide spiral can be launched in response to a write head crossing the pre-existing coarse guide spiral, rather than in response to a precisely timed event. To enable launch points being disposed on pre-existing coarse guide spirals, launch points are not all located at the same radial position on the recording surface.