Heat Actuator Contamination Removal for Accurate Head-Media Spacing
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Solution Overview
Problem
In hard disk drive systems, especially those using heat-assisted magnetic recording (HAMR), contamination on the magnetic recording head can lead to incorrect detection of head-media spacing due to elevated temperatures, resulting in early contact triggers and potential damage.
Innovation Solution
A method involving setting a heat actuator to a first power level, dwelling for a specified time to remove contamination, oscillating the actuator to a lower power level while detecting periodic contact between the head and disk, calculating the amplitude of contact using discrete Fourier transform techniques, and correlating it to clearance distance, thereby avoiding early contact triggers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the heat actuator power is increased to compensate for head contamination, then the head-media spacing detection becomes inaccurate, but reducing the power leads to insufficient heat generation for accurate contact detection
Solution Approach 1:
The patent applies preliminary action by performing a contamination removal dwell period at a first power level before conducting contact detection at a second power level. This preliminary dwell allows contamination to be removed from the head surface, ensuring that subsequent contact detection is not affected by residual contaminants that would cause early contact triggers.
Solution Approach 2:
The patent implements periodic action by establishing a repeated cycle where the heat actuator is cycled between a first power level (for contamination removal) and a second power level (for contact detection). This periodic cycling ensures that contamination is removed before each contact detection measurement, maintaining measurement accuracy over time.
2Reliability
If the dwell time at first power level is increased to remove contamination, then contamination removal effectiveness improves, but the overall measurement time increases
Solution Approach 1:
The patent applies parameter changes by optimizing the dwell time at the first power level based on detected contamination conditions. The dwell time is not fixed but is adjusted according to the specific contamination state of the head, allowing sufficient contamination removal while minimizing unnecessary time delay. The system monitors and adapts the dwell time parameter to balance effectiveness and 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 method effectively removes head contamination during each heat actuator power step, ensuring accurate detection of head-media spacing and preventing damage by maintaining a consistent clearance, thus enhancing the reliability and performance of magnetic recording systems.
Implementation Method 1
setting a heat actuator at a first power level, dwelling at the first power level for a specified length of time, removing contamination from the head during the specified dwell time
Implementation Method 2
detecting periodic contact between the head and an adjacent disk, calculating the amplitude of the detected periodic contact
Data Source
AI summary
A method of removing contamination from a magnetic recording head during contact detection, including the steps of setting a heat actuator at a first power level, dwelling at the first power level for a specified length of time, removing contamination from the head during the specified dwell time, oscillating the heat actuator from the first power level to a second level that is lower than the first level while detecting periodic contact between the head and an adjacent disk, calculating the amplitude of the detected periodic contact, and correlating the calculated amplitude to a clearance distance between the head and the disk.