Magnetic Recording Medium Width Stability via Tension Control
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Solution Overview
Problem
Magnetic recording media face challenges in maintaining constant width due to dimensional changes caused by environmental factors, such as temperature and humidity changes, which can lead to off-track phenomena during data storage and retrieval.
Innovation Solution
A magnetic recording medium with a specific layer structure, including a magnetic layer and a base layer, having an average thickness of ≤5.6 μm, a dimensional change of ≤660 ppm/N in the width direction with tension adjustment, and a servo pattern recorded on the magnetic layer, along with a controlled friction coefficient and surface roughness, to maintain stability and precision in data storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the track width and distance between tracks are narrowed to improve recording density, then the recording density is improved, but the allowable dimensional change amount becomes smaller
Solution Approach 1:
The patent applies parameter changes by controlling the Poisson's ratio (ρ≥0.25) and elastic limit value (σMD≥0.7N) of the magnetic recording medium to optimize its dimensional stability. By adjusting these material parameters, the medium can maintain constant width under tension while achieving narrow track widths for high recording density.
Solution Approach 2:
The patent uses composite material structure with a magnetic layer formed by sputtering or coating methods on a substrate. The composite structure allows optimization of both mechanical properties (for dimensional stability) and magnetic properties (for recording density), resolving the contradiction between narrow tracks and dimensional precision.
2Stability of the object's composition
If tension is increased in the longitudinal direction to suppress dimensional change, then the width stability is improved, but the friction with the head increases
Solution Approach 1:
The patent controls the friction coefficient (μ1M≤0.5) through parameter optimization of the magnetic layer surface properties. By adjusting surface roughness and material composition, the medium achieves adequate width stability under operating tension while maintaining acceptable friction levels for smooth head operation.
3Quantity of substance
If the thickness of the magnetic recording medium is reduced to increase recording capacity, then the recording capacity is improved, but the running stability may deteriorate
Solution Approach 1:
The patent optimizes the thickness parameter (tT≤5.6μm) in conjunction with controlling Poisson's ratio (ρ≥0.25) and elastic limit (σMD≥0.7N). This parameter optimization allows the medium to be thin enough for high recording capacity while maintaining sufficient mechanical strength and dimensional stability for reliable running.
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
The solution effectively suppresses dimensional changes in the magnetic recording medium, enhancing running stability and data storage precision by adjusting tension in the longitudinal direction, thereby maintaining a constant width and improving recording capacity.
Implementation Method 1
a magnetic layer and a base layer
Implementation Method 2
the magnetic layer may be a sputtered layer
Data Source
AI summary
There is provided a magnetic recording medium which has a layer structure including a magnetic layer and a base layer, and of which an average thickness tT is tT≤5.6 μm, a dimensional change amount Δw in a width direction with respect to a change in tension in a longitudinal direction is 660 ppm/N≤Δw, a servo pattern is recorded on the magnetic layer, a standard deviation σPES of a position error signal (PES) value obtained from a servo signal in which the servo pattern is reproduced is σPES≤25 nm, and a maximum value μ1M of a friction coefficient μ1 between a surface on a side of the magnetic layer and an LTO3 head in a case where measurement of the friction coefficient μ1 is performed 250 times is 0.04≤μ1M≤0.5.