Magnetic Head Assist Element Voltage Control for Stable Protrusion
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Solution Overview
Problem
Magnetic recording heads experience degradation due to self-heating of assist elements, leading to variations in protrusion and heat generation, which affects recording performance.
Innovation Solution
A controller adjusts the drive voltage of assist elements based on the amount of protrusion and environmental temperature to maintain a desired protrusion and reduce heat generation variations, thereby stabilizing the magnetic head's levitation and reducing degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the drive voltage is set to a desired value, then the assist element can operate with proper voltage, but the self-heating varies due to dimensional variations and shape variations, causing oxidation and degradation
Solution Approach 1:
The patent applies feedback control by detecting the actual protrusion amount of the assist element and adjusting the drive voltage accordingly. The controller measures protrusion (which correlates with temperature) and modifies the drive voltage to maintain optimal operating conditions, preventing both overheating and underperformance. This closed-loop approach resolves the contradiction by continuously adapting to dimensional variations.
Solution Approach 2:
The patent changes the drive voltage parameter dynamically based on the measured protrusion amount. By adjusting the voltage parameter in response to dimensional variations, the system maintains consistent thermal behavior and prevents oxidation. This parameter adaptation resolves the contradiction between maintaining proper voltage operation and compensating for temperature variations.
2Shape
If the drive voltage is increased to compensate for dimensional variations, then the protrusion amount can be maintained, but the heat generation increases causing oxidation
Solution Approach 1:
The feedback mechanism detects protrusion changes and adjusts drive voltage to match the actual dimensional state. This prevents excessive voltage application that would cause overheating and oxidation, while still maintaining adequate protrusion for proper operation. The system finds the optimal voltage point that satisfies both shape requirements and thermal constraints.
Solution Approach 2:
The drive voltage parameter is dynamically adjusted based on measured protrusion rather than using a fixed high value. This optimized parameter change approach maintains sufficient protrusion for functional performance while avoiding excessive heat generation that would cause oxidation and degradation.
3Object-affected harmful factors
If the drive voltage is decreased to reduce heat generation, then oxidation is prevented, but the protrusion amount becomes insufficient affecting recording performance
Solution Approach 1:
The feedback control system monitors protrusion and adjusts drive voltage to ensure sufficient protrusion for proper recording performance. This prevents the system from operating at excessively low voltages that would cause inadequate protrusion while still maintaining thermal management to prevent oxidation. The optimal operating point is dynamically determined.
Solution Approach 2:
The drive voltage is optimized by adjusting it based on actual protrusion measurements rather than using a fixed low value. This parameter adaptation ensures both adequate protrusion for recording functionality and sufficient thermal management to prevent oxidation, resolving the contradiction between performance and protection.
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 extends the life of assist elements by minimizing heat-induced degradation and maintaining consistent performance in magnetic recording heads.
Implementation Method 1
the self-heating of the element part may vary due to dimensional variations of the assist element
Implementation Method 2
When the amount of heat generated by the assist element is large, the assist element and the area near the element of the recording head may oxidize
Data Source
AI summary
According to one embodiment, a disk device includes a recording medium, a magnetic head including a recording head, an assist element, and a heater, and a controller including a heater voltage supply circuit, a drive voltage supply circuit configured to supply a drive voltage to the assist element, and a contact detection circuit. The controller adjusts a set value of the drive voltage based on an amount of protrusion of the assist element when contact is detected by the contact detection circuit.