Magnetic Recording Cartridge Width Stability
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Solution Overview
Problem
Magnetic recording cartridges face challenges in maintaining a constant width of the magnetic recording medium due to dimensional changes caused by environmental factors, which affects recording capacity and leads to issues like off-track phenomena and wrinkles during tension adjustment.
Innovation Solution
A magnetic recording cartridge with a magnetic recording medium having an average thickness of ≤5.6 μm, a dimensional change of 660 ppm/N or less in the width direction with tension change, and a squareness ratio of 65% or more, where the servo track width on the inner side of winding is greater than on the outer side, preventing wrinkles and maintaining stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the track width and distance between tracks are narrowed to improve recording density, then recording capacity is improved, but the maximum allowable dimensional change amount becomes smaller
Solution Approach 1:
The patent applies parameter changes by precisely controlling the thickness of the magnetic recording medium (5.0 to 5.6 μm) and adjusting the dimensional change characteristics (600 to 800 ppm/N) to resolve the contradiction between high recording density and tight dimensional tolerance
Solution Approach 2:
The patent uses composite material structures combining magnetic layers with specific thicknesses (35-90 nm) and back layers with controlled surface roughness (3.0-7.5 nm) to achieve both high recording density and stable dimensional properties
2Stability of the object's composition
If tension is adjusted in the longitudinal direction to suppress dimensional change, then width stability is improved, but wrinkles may occur during winding
Solution Approach 1:
The patent resolves this contradiction by optimizing the elastic limit value (0.7 to 1.5 N) and dimensional change characteristics (600 to 800 ppm/N) to allow tension adjustment for width stability while preventing wrinkle formation during winding operations
Solution Approach 2:
The patent applies preliminary action by pre-controlling the surface roughness of the back layer (3.0-7.5 nm) and the friction coefficient between layers (0.20-0.80) to prevent wrinkle formation before it occurs during tension adjustment
3Productivity
If the magnetic recording medium is made thinner to increase recording capacity, then recording density is improved, but dimensional stability becomes more difficult to maintain
Solution Approach 1:
The patent uses composite material structures with optimized layer thicknesses (magnetic layer: 35-90 nm, back layer: 0.5-2.0 μm) and controlled surface roughness to maintain dimensional stability despite the thin overall thickness (5.0-5.6 μm), thereby increasing recording capacity
Solution Approach 2:
The patent applies parameter changes by precisely controlling the thickness parameters within specific ranges and adjusting the dimensional change characteristics (600 to 800 ppm/N) to maintain stability while achieving high recording capacity
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 significantly increases recording capacity by maintaining the medium's width and preventing wrinkles, ensuring stable operation in recording and reproducing apparatuses that adjust tension longitudinally.
Implementation Method 1
a dimensional change amount Δw in a width direction with respect to a tension change in a longitudinal direction is 660 ppm/N≤Δw
Implementation Method 2
a thermal expansion coefficient α of the magnetic recording medium may be 5.5 ppm/° C.≤α≤9 ppm/° C.
Implementation Method 3
a humidity expansion coefficient β of the magnetic recording medium may be β≤5.5 ppm/% RH
Data Source
AI summary
A magnetic recording cartridge is provided and including a magnetic recording medium, wherein an average thickness of the magnetic recording medium tT is 3.5 μm≤tT≤5.6 μm, a dimensional change amount Δw in a width direction of the magnetic recording medium with respect to a tension change in a longitudinal direction of the magnetic recording medium is 700 ppm/N≤Δw≤20000 ppm, the magnetic recording medium is accommodated in a state of being wound around the reel in the cartridge case and (a servo track width on an inner side of winding of the magnetic recording medium)−(a servo track width on an outer side of winding of the magnetic recording medium)>0 is satisfied, and a squareness ratio measured in a vertical direction of the magnetic recording medium is 65% or more.