Asymmetric Write Head Yoke Lengths for Coil Volume
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Solution Overview
Problem
Conventional magnetic write heads have limited coil volume due to equal upper and lower yoke lengths, restricting the achievement of larger cross-sectional areas for coils and affecting write head efficiency.
Innovation Solution
The design decouples upper and lower yoke lengths, allowing for different lengths between the pole tip and back gap in each yoke, with coil turns in both, which increases efficiency and reduces coil resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If equal upper and lower yoke lengths are used in write heads, then manufacturing simplicity is maintained, but coil cross-sectional area is limited
Solution Approach 1:
The patent applies asymmetry by making the upper yoke length different from the lower yoke length. Specifically, the lower yoke has a greater length than the upper yoke, creating an asymmetric structure that increases the available volume for coil windings in the lower yoke region while maintaining functional performance of the write head
2Reliability
If larger coil cross-sectional areas are achieved through unequal yoke lengths, then coil resistance is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent segments the yoke structure into distinct upper and lower portions with different lengths. The lower yoke is extended relative to the upper yoke, creating separate regions that can be independently optimized for coil placement and magnetic flux pathways, thereby reducing coil resistance through larger cross-sectional area
Solution Approach 2:
The patent applies local quality by providing different yoke lengths at different locations of the write head. The lower yoke has a greater length specifically where coil windings are required, optimizing the local electrical properties (reducing resistance) without affecting the overall head structure uniformly
3Productivity
If unequal yoke lengths are implemented, then write head efficiency is enhanced, but structural symmetry is lost
Solution Approach 1:
The patent deliberately introduces asymmetry in the yoke structure, making the lower yoke longer than the upper yoke. This asymmetric design optimizes the magnetic flux distribution and coil placement to enhance write head efficiency, accepting the loss of structural symmetry as a necessary trade-off for improved performance
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 design enhances write head efficiency by up to 62% and reduces coil resistance by approximately 50%, with minimal loss in efficiency for longer lower back gap lengths, achieving better performance with a back gap.
Implementation Method 1
coil turns in the upper and lower yokes
Implementation Method 2
Thermal fly-height control (TFC) is a method of altering this distance between the transducers and the disk surface by heating the components of the reader/writer causing thermal expansion of the materials
Data Source
AI summary
According to one embodiment, a system comprises an upper yoke having a first length defined between a pole tip thereof and a back gap thereof. In addition, the system includes a lower yoke having a second length defined between a pole tip thereof and a back gap thereof, the second length being greater than the first length. Also, the system includes coil turns in the upper and lower yokes. Additional systems and methods are also presented.