Magnetic Disk Preheat Position Control for Bump Avoidance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional magnetic disk devices face challenges in efficiently controlling dynamic flying height (DFH) due to increased disk capacity and the risk of magnetic heads hitting bumps on the disk, leading to potential damage and inefficiencies in preheating processes.
Innovation Solution
A magnetic disk device with a controller that determines a preheat start position based on the time required for thermal expansion and the presence of bumps, adjusting the preheat start position if a bump is detected to avoid collisions and ensure timely preheating within the seek time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If preheating is started from a position several tracks before the target track, then preheating time is sufficient, but the magnetic head may hit bumps on the disk causing damage
Solution Approach 1:
The controller determines a preheat start scheduled position based on the remaining seek distance and the time required for preheating, starting preheating in advance from this calculated position rather than from a fixed position several tracks before the target. This preliminary action is optimized to provide sufficient preheating time while avoiding bump collision areas.
Solution Approach 2:
The preheat start position is made dynamic rather than fixed. The controller adjusts the preheat start scheduled position based on the current seek distance and preheating requirements. Additionally, when bumps are detected, the preheat start position is dynamically changed to an arbitrary position from the bump location to the seek target position, making the system adaptive to disk conditions.
2Device complexity
If the preheat start position is fixed several tracks before the target, then control is simple, but preheating efficiency decreases and head may collide with bumps
Solution Approach 1:
The preheat start position parameter is changed from a fixed value (several tracks before target) to a dynamically calculated value based on remaining seek distance and preheating time requirements. The controller calculates the preheat start scheduled position using these parameters, optimizing preheating efficiency while maintaining manageable control complexity through automated calculation.
3Manufacturing precision
If preheating starts earlier to ensure sufficient time, then thermal expansion is complete, but seek time is increased
Solution Approach 1:
Preheating is started in advance from the calculated preheat start scheduled position, ensuring that thermal expansion is complete before the magnetic head reaches the seek target position. This preliminary action is precisely timed based on the remaining seek distance and required preheating duration, ensuring magnetic spacing precision without excessive seek time.
Solution Approach 2:
The controller calculates the optimal preheat start scheduled position to minimize the preheating period while ensuring completion before reaching the target. By rushing through the preheating process at the optimal start position rather than starting excessively early, the system achieves required thermal expansion with minimized seek time loss.
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 allows for earlier and more efficient preheat control, preventing magnetic head collisions with bumps and maintaining disk quality by optimizing preheat timing and positioning.
Implementation Method 1
magnetic spacing of a magnetic head from a magnetic disk is adjusted by energizing a heater mounted on a head slider and thermally expanding the head slider
Data Source
AI summary
A magnetic disk device according to an embodiment includes: a head slider; a magnetic head provided in the head slider; a heater provided in the head slider; and a controller that determines, in seek operation of the magnetic head, a preheat start scheduled position from a remaining seek distance at which a time required for preheating of the head slider can be secured, the controller starting the preheating from the preheat start scheduled position in a case where no bump exists in an area from the preheat start scheduled position to a seek target position, the controller changing a preheat start position to an arbitrary position in an area from the bump to the seek target position in a case where the bump exists in the area from the preheat start scheduled position to the seek target position.