Dual Reader Shield Structure for High Density Storage
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Solution Overview
Problem
In magnetic data storage systems, the narrow shield-to-shield spacing (SSS) required for increasing recording density leads to a conflict between reducing pulse width (PW50) and maintaining performance under skew, as thick mid-shields are needed for stability but also degrade performance.
Innovation Solution
A stacked dual reader design with a thin solid mid-shield and side shields attached to the bottom shield, replacing thick antiferromagnetic (AFM) mid-shields, which improves PW50 and reduces SSS, enhancing signal-to-noise ratio (SNR) and stability under skew.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thick antiferromagnetic mid-shields are used, then stability under skew is maintained, but pulse width (PW50) increases and recording density decreases
Solution Approach 1:
The patent changes the physical parameters of the mid-shield by replacing thick antiferromagnetic material with thin ferromagnetic material having specific magnetic properties (saturation magnetization of 800-1200 emu/cc, perpendicular magnetic anomaly). This parameter change allows achieving both stability under skew and reduced pulse width, resolving the contradiction between reliability and length parameters.
Solution Approach 2:
The patent employs composite magnetic shield structures combining different magnetic materials with complementary properties. The thin ferromagnetic mid-shield is integrated with side shields and pole pieces to create a composite structure that provides both mechanical stability and optimized magnetic field control, enabling reduced PW50 while maintaining skew performance.
2Stability of the object's composition
If thick mid-shields are used, then structural stability is improved, but shield-to-shield spacing increases and signal-to-noise ratio decreases
Solution Approach 1:
The patent fundamentally changes the material parameters of the mid-shield from thick antiferromagnetic material to thin ferromagnetic material with optimized magnetic properties. This enables reducing the mid-shield thickness from micrometers to nanometers scale, thereby decreasing SSS while maintaining structural stability through magnetic rather than purely mechanical support.
Solution Approach 2:
The patent replaces mechanical support (thick physical structure) with magnetic support (field-based stabilization). The thin ferromagnetic mid-shield provides structural stability through magnetic field interactions and integration with the magnetic circuit, rather than relying on mechanical thickness, thus reducing SSS while maintaining stability.
3Productivity
If narrow shield-to-shield spacing is used, then recording density increases, but performance under skew deteriorates
Solution Approach 1:
The patent changes the magnetic parameters of the mid-shield material to achieve optimized magnetic field distribution in the narrow SSS configuration. The specific saturation magnetization range (800-1200 emu/cc) and perpendicular magnetic anomaly provide the right balance between field confinement for high density and field stability for skew resistance, resolving the contradiction between productivity and reliability.
Solution Approach 2:
The patent applies different magnetic properties to different regions of the shield structure. The thin mid-shield has optimized magnetic parameters for field confinement, while side shields and pole pieces have complementary properties for skew resistance. This local optimization allows narrow SSS for high density while maintaining overall performance under skew through distributed functional specialization.
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 implementation of a thin solid mid-shield in the stacked dual reader reduces PW50, increases SNR, and improves performance under skew conditions, providing better magnetic stability and higher recording density capabilities.
Implementation Method 1
a magnetoresistive (MR) sensor for retrieving magnetically encoded information stored on a magnetic disc. Magnetic flux from the surface of the disc causes rotation of the magnetization vector of a sensing layer of the MR sensor, which in turn causes a change in electrical resistivity of the MR sensor
Data Source
AI summary
Implementations described and claimed herein provide a dual reader wherein a bottom shield is attached to side shields.