Asymmetric Magnetic Write Heads for Shingled Recording
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Solution Overview
Problem
The existing magnetic data recording systems face limitations in reducing track pitch and increasing data density due to the size of the write pole, which restricts the reduction of write pole size necessary for reliable data writing, and shingled recording introduces design and performance challenges.
Innovation Solution
The use of asymmetrical magnetic write heads, with some being mirror images of others, allows for efficient shingled magnetic recording by predominantly writing to a desired side of the write pole, facilitating improved speed and performance by ensuring correct orientation of writing edges relative to the disk's diameter, regardless of recording direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the write pole size is reduced to decrease track pitch, then data density is improved, but the magnetic write field strength deteriorates making reliable data writing difficult
Solution Approach 1:
The write pole is designed with an asymmetric cross-sectional shape where the first dimension (width) is smaller than the second dimension (height). This asymmetry allows the pole to generate a concentrated magnetic write field in the critical dimension for writing, achieving reliable data recording with a smaller effective write pole size, thereby enabling decreased track pitch and increased data density
Solution Approach 2:
The asymmetric write pole concentrates the magnetic flux distribution locally, creating a stronger and more focused magnetic write field at the critical interface with the magnetic medium. This local concentration of magnetic field strength enables reliable writing despite the overall reduced pole size
2Quantity of substance
If shingled magnetic recording is implemented to increase data density, then track spacing is reduced, but design complexity and performance challenges increase
Solution Approach 1:
The asymmetric write pole geometry is specifically designed to work with shingled magnetic recording by creating a magnetic write field that predominantly writes to one side of the track. This asymmetric field distribution simplifies the shingled recording design by eliminating the need for complex head orientation adjustments and actuator movements, reducing design complexity while enabling increased data density
3Length of stationary object
If the write pole size is reduced to decrease track pitch, then data density is improved, but the magnetic write field strength deteriorates
Solution Approach 1:
The write pole employs an asymmetric cross-section with different dimensions in two perpendicular directions. The smaller first dimension enables reduced track pitch, while the larger second dimension maintains sufficient magnetic write field strength, thus resolving the contradiction between decreasing track pitch and maintaining write field strength
Solution Approach 2:
The asymmetric pole shape concentrates magnetic flux locally at the pole tip interface with the medium, creating a high-density magnetic write field in the critical region. This local flux concentration compensates for the reduced overall pole size, maintaining adequate write field strength despite smaller track pitch
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 the speed and performance of the disk drive system by optimizing writing performance at the appropriate edge of the write pole, enabling efficient shingled magnetic recording without the need for excessive actuator movement.
Implementation Method 1
An electrically conductive write coil is wrapped around the write pole and induces a magnetic flux that magnetizes the write pole when a current is passed through the coil. This results in a magnetic write field being generated through the adjacent magnetic medium
Implementation Method 2
The magnetic write field locally magnetizes the medium and then travels through the medium and returns to the write head at the location of the return pole
Implementation Method 3
A magnetoresistive sensor such as a GMR or TMR sensor can be employed for sensing magnetic fields from the rotating magnetic disk. In a read mode, the resistance of the spin valve sensor changes proportionally to the magnitudes of the magnetic fields from the rotating disk
Data Source
AI summary
A magnetic disk drive system configured for shingled magnetic data recording wherein data tracks are recorded in an overlapping fashion on a magnetic media. The disk drive system includes magnetic write heads that are asymmetric so as to have increased writing at one side of the write head. The magnetic disk drive system includes magnetic write heads that are mirror images of one another so that write heads located at opposite surfaces of the magnetic media (e.g. one head facing up and one facing down) end up having preferential writing in the location relative to inner and outer diameters of the magnetic media.