Bit Patterned Magnetic Storage Medium Servo Sector Design
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Solution Overview
Problem
Conventional magnetic disc drives face limitations in areal density due to superparamagnetism, and existing servo systems are incompatible with bit patterned magnetic storage media, hindering precise head positioning for high-density recordings.
Innovation Solution
A bit patterned magnetic storage medium with first and second adjoining servo sectors, where the discrete magnetic elements in one row are substantially aligned and offset in the track direction relative to corresponding elements in the other row, allowing for precise head positioning and increased areal density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the grain size is decreased to increase areal density, then more bits can be stored on the disc area, but superparamagnetism occurs causing magnetization to randomly change direction
Solution Approach 1:
The magnetic layer is divided into discrete, isolated magnetic elements (islands) separated by non-magnetic material. Each island is a single grain that stores one information bit, preventing the superparamagnetic effect from causing random magnetization changes across the entire grain structure while maintaining high areal density through precise positioning of these segmented elements.
2Ease of operation
If conventional null patterns are used for servo control, then head positioning can be maintained on granular media, but the patterns are incompatible with bit patterned magnetic storage media
Solution Approach 1:
The servo sectors use discrete magnetic elements with specific positional relationships (offset between rows, alignment within rows) that are locally optimized for bit patterned media. This local structural quality enables the servo system to function specifically for patterned media rather than attempting to adapt conventional patterns.
3Quantity of substance
If discrete magnetic elements are used with precise positioning, then higher areal density is achieved, but the servo system requires new patterns incompatible with conventional media
Solution Approach 1:
The servo sector structure employs asymmetric positioning where the first and second rows of magnetic elements have different characteristics - one row is offset relative to the other in the track direction. This asymmetric arrangement encodes positional information efficiently, enabling precise head positioning without requiring complex symmetric patterns, thus achieving high areal density with manageable servo complexity.
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
Enables higher areal density storage by allowing precise alignment and offsetting of magnetic elements, enhancing the servo system's ability to accurately position the read/write head over small magnetic elements, thus overcoming the limitations of conventional media.
Implementation Method 1
data are stored on one or more discs, which are coated with a thin magnetically hard layer. The magnetic layer itself is composed of a single sheet of very fine, single-domain grains
Implementation Method 2
Superparamagnetism puts an areal density limit of 0.5 Tb/in2 for perpendicular recording
Data Source
AI summary
A magnetic storage medium comprises a plurality of discrete magnetic elements and first and second adjoining servo sectors. Each of the servo sectors comprises first and second rows of the discrete magnetic elements extending in a track direction. The second row of the discrete magnetic elements are stacked relative to the discrete magnetic elements of the first row in a cross-track direction that is perpendicular to the track direction. The discrete magnetic elements of the first servo sector are staggered in the cross-track direction relative to the discrete magnetic elements of the second servo sector.