HAMR Laser Modulation for Static Head-Media Spacing Compensation
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Solution Overview
Problem
Conventional data storage systems face performance and reliability issues due to variations in static head-media spacing (HMS) in magnetic recording systems, which are not effectively addressed by existing compensation methods, particularly in Heat Assisted Magnetic Recording (HAMR) systems.
Innovation Solution
A method and apparatus that modulate a source of electromagnetic radiation to heat the storage medium based on control signals representing static deviations in HMS, allowing for compensation of static and nonlinear transition shifts by altering the temperature profile and applying a magnetic field, thereby adjusting the spacing and transition locations in the storage medium.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If heat is applied to the write head to cause the pole tip to protrude for achieving desired static HMS, then the static HMS variation is compensated, but the device complexity increases due to requiring preamp-powered heaters and factory calibration routines
Solution Approach 1:
The patent replaces the mechanical heating approach (using preamp-powered heaters on the write head) with an electromagnetic radiation source (laser) that optically heats the storage medium. This substitution eliminates the need for complex heater integration into the head assembly and factory calibration routines, while achieving the same goal of adjusting head-media spacing through thermal expansion of the medium.
Solution Approach 2:
The patent changes the physical state of the storage medium by applying electromagnetic radiation to heat it, causing thermal expansion that adjusts the head-media spacing. This parameter change (temperature-induced expansion) provides a simpler alternative to mechanical heating of the head, as it requires no integration of heating elements into the head assembly and automatically compensates for static HMS variations.
2Reliability
If the head is designed to fly at a constant height to meet system performance measures, then system reliability is improved, but static HMS deviations occur due to manufacturing variations in head and media combinations
Solution Approach 1:
The patent implements a feedback mechanism where the electromagnetic radiation source continuously adjusts the temperature of the storage medium based on the required head-media spacing. This active compensation system counteracts static HMS deviations caused by manufacturing variations, ensuring the head maintains its optimal flying height for reliable system performance without requiring precise manufacturing tolerances.
Solution Approach 2:
The patent uses thermal expansion of the storage medium as a compensatory mechanism. By controlling the temperature of the medium through electromagnetic radiation, the system adjusts the physical dimensions of the medium itself, thereby compensating for manufacturing variations in head-media spacing and maintaining consistent flying height for improved reliability.
3Manufacturing precision
If laser power is modulated to compensate static HMS variations, then transition locations are adjusted and nonlinear transition shift is compensated, but energy consumption increases
Solution Approach 1:
The patent modulates the temperature parameter of the storage medium using electromagnetic radiation to achieve two goals simultaneously: compensating static HMS variations and correcting nonlinear transition shifts. By controlling the degree of thermal expansion, the system adjusts both the head-media spacing and the magnetic transition locations, providing dual compensation with a single parameter control mechanism.
Solution Approach 2:
The electromagnetic radiation source serves multiple functions: it heats the storage medium to compensate for static head-media spacing variations and simultaneously adjusts the magnetic transition locations to correct nonlinear transition shifts. This multi-functional approach consolidates what would otherwise require separate compensation mechanisms into a single energy input, improving overall system efficiency.
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 effectively compensates for static HMS variations and nonlinear transition shifts, improving system performance by adjusting the temperature profile and magnetic transitions, leading to enhanced signal energy and reduced Inter-Symbol-Interference (ISI) and miss-equalization, thus increasing the overall reliability and efficiency of the HAMR system.
Implementation Method 1
modulating a source of electromagnetic radiation to heat a portion of the storage medium
Implementation Method 2
applying a magnetic field to the storage medium to cause magnetic transitions in the storage medium
Implementation Method 3
transition locations in the storage medium are changed by changing a temperature profile in the storage medium
Data Source
AI summary
An apparatus comprises a storage medium, a recording head, a source of electromagnetic radiation, and a control circuit for modulating the source of electromagnetic radiation in response to a static deviation of a spacing between the recording head and the storage medium. A method of compensating a static deviation of a spacing between a recording head and a storage medium performed by the apparatus, and a method of precompensating for nonlinear transition shifts in a heat assisted magnetic recording system, are also provided.