Magnetic Disc Zone Width Optimization for Data Capacity
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Solution Overview
Problem
Magnetic disc apparatuses face challenges in maximizing data storage area due to inefficient servo pattern division methods, which result in suboptimal servo area utilization and reduced data area capacity.
Innovation Solution
The magnetic disc apparatus divides the disc into multiple zones with varying servo pattern frequencies and zone widths, where the outer zones have wider widths than inner zones, allowing for reduced servo pattern areas and increased data areas, while ensuring correct servo processing by overlapping servo patterns and using zone servo switching units to adjust servo frequencies and gate generation timings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the servo pattern division method is used with equal zone widths, then the disc can be divided into multiple zones with different servo pattern frequencies, but the servo area occupancy is not minimized and data area capacity is reduced
Solution Approach 1:
The patent applies local quality by making zone widths non-uniform across the disc radius. Specifically, the zone width at any radial position is determined by a function that makes it larger near the inner radius and smaller near the outer radius. This local variation in zone width optimizes the balance between servo area and data area capacity, allowing the servo area occupancy to be minimized while maintaining proper servo pattern distribution across different zones.
2Productivity
If the servo pattern frequency is increased in outer zones, then more servo patterns can be accommodated, but the zone width must be reduced which decreases data area capacity
Solution Approach 1:
The patent employs parameter changes by varying both the servo pattern frequency and zone width as continuous functions of radial position. The zone width w(r) is defined by a function involving parameters alpha and beta, where alpha controls the overall width scaling and beta controls the radial distribution characteristic. By optimizing these parameters, the system achieves higher servo pattern frequencies in outer zones while maintaining adequate data area capacity through the non-uniform width distribution.
3Area of stationary object
If zone widths are made non-uniform to optimize data area, then servo area occupancy is minimized, but the servo processing timing becomes more complex
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing the optimal zone width distribution function w(r) before actual servo operations. The function, which depends on parameters alpha and beta, is determined in advance based on the desired balance between servo area occupancy and data area capacity. During operation, this pre-determined width function guides the zone boundary placement, simplifying the real-time servo processing control while achieving optimized area distribution.
Data Source
AI summary
According to one embodiment, a magnetic disc has N (N is an integer of 2 or more) zones divided in a radial direction, and servo patterns different in servo pattern frequency are recorded in the individual zones. The relationship that the zone width of a K-th (K is an integer of 1 or more and N−1 or less) zone from the outer radial side of the magnetic disc is larger than the zone width of the K+1-th zone adjacent to the K-th zone on the inner diameter side applies to all the K-th zones in which K is 1 or more and N−1 or less.