Write Head Gap Current Balancing for Higher Areal Density
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Solution Overview
Problem
Current write heads in hard-disk drives face challenges in achieving optimal current-assisted areal density capacity (ADC) gains due to uneven current distribution, which leads to writability degradation and additional adjacent track interference (ATI) as dimensions scale down.
Innovation Solution
The implementation of a non-dual-write-shield (nDWS) write head structure with optimized gap current distribution, utilizing insulators and resistors to balance current flow between the write gap and side/leading gaps, and incorporating shunting paths to reduce path resistances, thereby enhancing current distribution and minimizing ATI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current write heads use conventional current distribution, then the structure is simple, but the current distribution is uneven leading to writability degradation and additional adjacent track interference
Solution Approach 1:
The write head structure is segmented into multiple functional components: main pole (MP), trailing shield (TS), side shields (SS), leading shield (LS), and write shield (WS). Each segment serves a specific purpose in directing and controlling current flow paths to achieve uniform current distribution across the write gap, thereby improving writability while managing structural complexity through functional specialization.
Solution Approach 2:
Different regions of the write head are assigned different electrical properties through strategic placement of insulators and resistors. The insulators are positioned at specific locations to block current leakage paths, while resistors are placed to balance current distribution across parallel paths. This local modification of electrical characteristics ensures uniform current density in the write gap without requiring complete redesign of the entire structure.
2Quantity of substance
If write head dimensions are scaled down to increase storage density, then the areal density capacity increases, but the current distribution becomes more uneven causing additional adjacent track interference
Solution Approach 1:
Insulators and resistors are introduced as intermediary elements that mediate the current flow between different parts of the write head. The insulators act as barriers to prevent current from taking unintended paths through the side and leading shields, while resistors provide controlled resistance to balance the current distribution. These intermediaries ensure that even in scaled-down dimensions, the current flows uniformly through the write gap, minimizing adjacent track interference while maintaining high areal density capacity.
3Power
If more current is directed through the write gap to improve ADC gain, then the current-assisted areal density capacity increases, but the current distribution becomes uneven increasing path resistance variations
Solution Approach 1:
The electrical parameters of the write head are modified by introducing resistors with specific resistance values at strategic locations. These resistors change the overall resistance distribution in the parallel current paths, allowing balanced current flow through the write gap and side/leading gaps. By carefully selecting resistor values, the system achieves uniform current distribution that maximizes ADC gain while avoiding excessive path resistance variations, thus managing the complexity of current distribution control.
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 optimized current distribution in the nDWS structure achieves up to ˜1.5% additional ADC gain, reduces ATI, and improves writability by ensuring equal current flow across different gaps, thus enhancing the performance of hard-disk-drive storage devices.
Implementation Method 1
a coil wrapped around the MP through a PP3 shield that is configured to direct a time-dependent write current to saturate magnetization of the MP
Implementation Method 2
The WG element can include a small giant-magnetoresistive (GMR) device with a thickness equal to that of the WG
Implementation Method 3
the WS is electrically isolated from the SS via an insulator, the insulator starting a first distance from the MP and ends at a second distance from the MP
Data Source
AI summary
The present embodiments can generally provide a magnetic write head structure with optimized gap current distribution to maximize the current-assisted areal density capacity (ADC) gain in hard-disk-drive storage devices. In a first example embodiment, a non-dual-write-shield (nDWS) write head can include a main pole (MP), a trailing shield (TS), and a write gap (WG) disposed between the MP and the TS. The write head can also include a side shield (SS), a leading shield (LS), and a write shield (WS). The write head can include a side gap (SG) between the MP and the SS on both sides of the MP tip, and a leading gap (LG) between the MP and the LS. The write head can also include a coil wrapped around the MP through a PP3 shield that is configured to direct a time-dependent write current to saturate magnetization of the MP.