Magnetic Recording Medium With Low Longitudinal Squareness

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Solution Overview

Problem

Current magnetic recording media face challenges in achieving excellent recording and reproducing characteristics due to limitations in squareness ratio and noise suppression in the longitudinal direction of the base substrate.

Innovation Solution

A magnetic recording medium is designed with a long-shaped flexible base substrate, a soft magnetic layer, and a specific magnetic recording layer configuration where the squareness ratio in the longitudinal direction is set to 30% or less, and the magnetization hard axis of the soft magnetic underlayer is aligned with the machine direction to improve reproduction output and suppress noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If a conventional magnetic recording medium with higher squareness ratio is used, then magnetic storage capacity is improved, but noise from domain wall displacement increases and reproduction output decreases

Engineering Contradiction:

Improvemagnetic storage capacityVSAvoidnoise from domain wall displacement

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The patent changes the squareness ratio parameter from conventional high values to 30% or less, fundamentally altering the magnetic properties of the soft magnetic underlayer. This parameter change enables the suppression of domain wall displacement noise while maintaining adequate magnetic storage capacity through the optimized magnetic layer structure.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies different magnetic properties to different layers: the soft magnetic underlayer has low squareness ratio (≤30%) to suppress noise, while the magnetic recording layer maintains high perpendicular magnetic anisotropy for data storage. This local differentiation of magnetic qualities resolves the contradiction between noise suppression and storage capacity.

Inventive Principle:

Principle #3Local quality

2Ease of manufacture

If a conventional magnetic recording medium is used, then manufacturing simplicity is maintained, but recording and reproducing characteristics are insufficient

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidrecording and reproducing characteristics

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent employs a composite structure with multiple layers having different magnetic properties: a soft magnetic underlayer with low squareness ratio, a magnetic recording layer with high perpendicular anisotropy, and intermediate layers. This composite material approach improves recording and reproducing characteristics while maintaining compatibility with existing manufacturing processes.

Inventive Principle:

Principle #40Composite materials

3Object-affected harmful factors

If the magnetization easy axis is aligned with the longitudinal direction, then noise suppression is improved, but reproduction output decreases

Engineering Contradiction:

Improvenoise suppressionVSAvoidreproduction output

Core Design Contradiction:

Object-affected harmful factorsVSPower

Solution Approach 1:

The patent creates different magnetic axis orientations in different layers: the soft magnetic underlayer has its magnetization easy axis aligned with the longitudinal direction for noise suppression, while the magnetic recording layer maintains perpendicular magnetization for high reproduction output. This local differentiation resolves the contradiction.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent transitions from in-plane magnetization alignment (longitudinal direction) to perpendicular magnetization in the recording layer. By utilizing the perpendicular dimension for the recording layer while keeping the underlayer in-plane aligned, the patent achieves both noise suppression and high reproduction output.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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

This configuration enhances recording and reproducing characteristics by achieving high reproduction output and reducing noise caused by domain wall displacement, allowing for a surface recording density 10 times that of existing tapes and enabling large-capacity data storage.

Implementation Method 1

a soft magnetic layer... wherein a squareness ratio in a longitudinal direction of the base substrate is 30% or less

Methodology Applied

Scientific EffectMagnetic anisotropy: Anisotropy

Implementation Method 2

a perpendicular magnetic recording medium in which a CoCrPt-based metallic material having a high magnetic anisotropy is subjected to crystal orientation in a perpendicular direction

Methodology Applied

Scientific EffectPerpendicular magnetic recording: Magnetism

Data Source

PatentUS10529367B2Magnetic recording medium

Publication Date: 2020.01.07 SONY GROUP CORP

AI summary

A magnetic recording medium includes a long-shaped base substrate having flexibility, a soft magnetic layer, and a magnetic recording layer. A squareness ratio in a longitudinal direction of the base substrate is equal to or less than a squareness ratio in a short-side direction of the base substrate. The squareness ratio in the longitudinal direction of the base substrate is 30% or less.