HDD Head Floating Control via Thermal Expansion
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Solution Overview
Problem
The inconsistency in head floating amounts within hard disk drives (HDDs) leads to issues such as head crashes, deteriorated electromagnetic conversion efficiency, and read errors, as the existing methods fail to effectively control the head floating amount to an optimum value, especially when the inconsistency among heads is large or when the floating amount is small.
Innovation Solution
A head floating amount control method and unit that utilizes a heater to thermally expand the head, detecting thermal asperity or read errors to determine the heating amount, which is then used to control the head floating amount to an optimum value based on the relationship between the heating amount and thermal expansion, thereby stabilizing the head output characteristic and preventing head crashes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the floating amount of the head is reduced to improve recording density and electromagnetic conversion efficiency, then the read and write performance is improved, but the head becomes susceptible to head crashes and thermal asperity errors
Solution Approach 1:
The patent applies parameter changes by heating the head to induce thermal expansion, thereby dynamically adjusting the head floating amount. By controlling the temperature of the head, the floating amount is optimized to maintain both high recording density and adequate safety margin against head crashes and thermal asperity errors
Solution Approach 2:
The patent directly utilizes thermal expansion by heating the head with a heater element. The thermal expansion of the head material causes the head to move away from the disk surface, increasing the floating amount. This allows the system to maintain optimal floating characteristics even at high recording densities where the head would naturally be too close to the disk
2Reliability
If the floating amount is increased to prevent head crashes and thermal asperity, then head reliability is improved, but electromagnetic conversion efficiency deteriorates due to increased magnetic spacing
Solution Approach 1:
The patent dynamically adjusts the head temperature and floating amount based on operating conditions. By controlling the heating parameter, the system maintains the floating amount within an optimal range that prevents head crashes while minimizing the negative impact on electromagnetic conversion efficiency
Solution Approach 2:
The patent makes the head floating amount dynamic rather than fixed. By continuously or periodically adjusting the head temperature and thus the floating amount, the system adapts to maintain optimal performance characteristics, preventing both head crashes and excessive magnetic spacing
3Adaptability or versatility
If conventional head floating characteristics are used to absorb inconsistency among individual heads, then manufacturing variability is tolerated, but the margin for head disk interference deteriorates when floating amount is small
Solution Approach 1:
The patent implements self-service by enabling each head to automatically adjust its own floating amount through heating. Each head can individually compensate for manufacturing inconsistencies and adapt to its specific characteristics, eliminating the need to design for the worst-case scenario and thereby improving the head disk interference margin
Solution Approach 2:
The patent changes the floating amount parameter individually for each head by applying controlled heating. This allows each head to optimize its floating characteristics based on its specific manufacturing variations, improving both consistency absorption and head disk interference margin simultaneously
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 solution optimizes the head floating amount to improve read and write performance, enhance storage apparatus reliability, and prevent thermal asperity-induced errors by maintaining a consistent head floating characteristic across individual heads, thus stabilizing the head output and reducing error rates.
Implementation Method 1
a head floating amount control method for controlling a head floating amount of each of a plurality of heads respectively having a heater, with respect to a recording medium... utilizing a heater to thermally expand the head
Implementation Method 2
detecting thermal asperity or read errors to determine the heating amount, which is then used to control the head floating amount
Data Source
AI summary
A head floating amount control unit control a head floating amount of each of a plurality of heads respectively having a heater, with respect to a recording medium, by detecting contact between each head and a corresponding recording medium by detecting a thermal asperity or a read error, and judging a heating amount of the heater at a time when the contact is detected as a state where the head floating amount is zero, and controlling the head floating amount of each head to an optimum head floating amount based on a relationship of the heating amount of the heater and an amount of thermal expansion of each head.