Disk Writing Mode Timing Control for Main Pole Relaxation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In magnetic disk drives, the main pole of a write bubble can extend several bit periods, leading to indistinct transitions when a bit transition occurs before the bubble relaxes, causing negative impacts on the magnetic profile and resulting in blurry bit transitions.
Innovation Solution
A method is introduced where the signal applied to the write head includes an initial pulse followed by a steady-state write current, with the steady-state current being turned off prior to the end of the write duration for pulse lengths greater than 1 T, allowing the main pole to relax and improving the magnetic profile for sharper transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the main pole is maintained at full write current throughout the write duration, then the write stability is improved, but the bit transition sharpness deteriorates due to extended main pole duration
Solution Approach 1:
The write current is segmented into three distinct phases: initial pulse phase (high current for reliable writing), steady-state phase (reduced current for controlled relaxation), and shut-off phase (current turned off before transition). This segmentation allows each phase to optimize for its specific function, resolving the contradiction between write stability and transition sharpness.
Solution Approach 2:
The write current is made dynamic rather than static, transitioning from high amplitude during initial pulse to reduced amplitude during steady-state, and finally to zero during shut-off. This dynamic adjustment allows the main pole to relax controllably while maintaining write stability during the critical initial writing phase.
2Loss of energy
If the steady-state write current is maintained until the end of write duration, then the energy efficiency is improved, but the main pole relaxation is delayed causing blurry transitions
Solution Approach 1:
The main pole relaxation is initiated prematurely by turning off the steady-state write current before the end of the write duration. This preliminary action allows the main pole to begin relaxing early, ensuring sharp transitions are achieved without requiring continuous high energy consumption throughout the entire write duration.
Solution Approach 2:
The write current is applied in periodic phases rather than continuously: initial pulse phase, steady-state phase, and shut-off phase. This periodic application of current allows energy to be consumed only when necessary for writing, while periods of reduced or zero current allow for main pole relaxation and sharp transitions.
3Manufacturing precision
If the shut-off pulse is initiated earlier to allow main pole relaxation, then the bit transition sharpness is improved, but the timing control complexity increases
Solution Approach 1:
The timing control circuit incorporates feedback mechanisms to monitor the write duration and automatically determine when to transition between phases. The control logic uses the known write duration parameters to calculate optimal shut-off timing, reducing the need for complex manual timing adjustments while maintaining sharp transitions.
Solution Approach 2:
The system changes timing parameters dynamically based on the write duration. The shut-off adjustment is calculated as a function of the write duration, allowing the timing control to adapt automatically to different write scenarios. This parameter-based approach simplifies control complexity by using mathematical relationships rather than complex timing logic.
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 approach enables sharper bit transitions by allowing the main pole to demagnetize before the end of the write duration, enhancing the magnetic profile and reducing the likelihood of indistinct transitions.
Implementation Method 1
a write head for writing data onto the magnetic data storage medium
Implementation Method 2
allowing the main pole to relax and improving the magnetic profile for sharper transitions
Data Source
AI summary
When writing data to a magnetic data storage medium, it is detected whether duration, before occurrence of a data transition, of data to be written exceeds a predetermined threshold. When the duration, before the transition, of the data to be written exceeds the predetermined threshold, the data is written by applying an initial pulse and then maintaining, until a shut-off pulse, a steady-state write current having an amplitude less than the initial pulse. A shut-off adjustment is determined based on a predetermined delay. The shut-off pulse is initiated at a time based on one bit period prior to the transition, adjusted by the shut-off adjustment. When the duration, before the transition, of the data to be written is at most equal to the predetermined threshold, the data is written by applying the initial pulse without applying a steady-state write current before the transition.