Magnetic Disk Device Dual-Head Spiral Pattern Writing
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Solution Overview
Problem
Magnetic disk devices face challenges in writing spiral servo patterns due to adjacent patterns intersecting or being too close, leading to data loss and impaired on-track or seek operations.
Innovation Solution
A magnetic disk device with dual heads and a controller that alternately activates them to write spiral patterns on opposite surfaces of a disk, maintaining a predetermined speed and interval to prevent data loss by distributing CGS servo patterns across multiple surfaces, ensuring they do not intersect or overlap.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple spiral servo patterns are written on a single disk surface, then the disk can be utilized more efficiently, but adjacent patterns may intersect or become too close causing data loss
Solution Approach 1:
The patent transitions from writing spiral patterns on a single disk surface to utilizing multiple disk surfaces (top and bottom). By distributing CGS servo patterns across different surfaces, the system increases the available writing space without reducing the radial or circumferential spacing between adjacent patterns, thus preventing data loss while improving disk utilization efficiency.
Solution Approach 2:
The patent divides the writing task across multiple disk surfaces by assigning odd-numbered CGS servo patterns to one surface and even-numbered patterns to another surface. This segmentation allows each surface to contain well-spaced patterns while collectively utilizing both surfaces of the disk, resolving the contradiction between efficiency and data integrity.
2Productivity
If the radial velocity of the head is increased to improve writing speed, then productivity increases, but the precision of spiral pattern positioning deteriorates
Solution Approach 1:
The patent implements periodic switching between odd and even numbered CGS servo pattern writing on alternating disk surfaces. This periodic action allows the system to maintain moderate writing speeds while distributing the high-precision positioning requirements across multiple surfaces, preventing data loss from pattern intersection and enabling more patterns to be written overall.
Data Source
AI summary
A magnetic disk device includes a disk, first and second heads, a motor, and a controller. The disk includes a first surface and a second surface opposite to the first surface. The first head is configured to perform reading and writing with respect to the first surface. The second head is configured to perform reading and writing with respect to the second surface. The motor is configured to move the first and second heads with respect to the first and second surfaces, respectively, along a radial direction of the disk. The controller is configured to alternately activate the first and second heads to perform writing of a plurality of spiral patterns on the first and second surfaces of the disk, respectively, while controlling the motor to move the first and second heads at a predetermined constant speed with respect to the first and second surfaces in the radial direction.