HAMR Slider Flying Height Compensation via Thermal Expansion
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Solution Overview
Problem
The challenge in hard disk drives is to accurately control the flying height of sliders over magnetic media due to heating from radiation sources, which can lead to unstable slider dynamics and data imprint errors, especially as storage densities increase and flying heights decrease.
Innovation Solution
A method and apparatus that include a radiation source submount, a temperature sensor, and a waveguide to adjust the flying height of a slider based on temperature changes, using a temperature sensor to measure the difference between the radiation source temperature and ambient temperature, and compensating for this change to maintain stable flying height.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high power laser radiation is used for HAMR heating, then rapid heating of magnetic media is achieved, but slider body expansion and flying height changes occur
Solution Approach 1:
The patent changes the physical state parameter of the slider body by introducing a temperature-dependent expansion coefficient. The slider body is designed with materials or structures that have specific thermal expansion characteristics, allowing the system to compensate for heating-induced dimensional changes. This enables the slider to maintain stable flying height despite high-power laser heating of the radiation source.
Solution Approach 2:
The patent directly addresses thermal expansion effects by designing the slider body to account for heating-induced dimensional changes. The slider structure incorporates thermal expansion compensation mechanisms that counteract the expansion caused by laser heating, thereby maintaining consistent flying height and preventing write element slider-media contact.
2Quantity of substance
If flying height is reduced to increase storage density, then data density is improved, but slider stability deteriorates
Solution Approach 1:
The patent introduces temperature as a controlling parameter that affects slider body dimensions. By monitoring and compensating for temperature-induced expansion, the system maintains stable flying height at reduced distances, enabling higher storage density without sacrificing slider stability.
Solution Approach 2:
The patent implements a feedback mechanism that monitors flying height changes and adjusts the slider position accordingly. This closed-loop control compensates for thermal expansion effects and maintains stable flying height, allowing operation at reduced flying heights for high-density storage.
3Power
If radiation source heating is increased for rapid media heating, then HAMR performance is improved, but write element contact with media occurs
Solution Approach 1:
The patent uses thermal expansion compensation to counteract the slider body expansion caused by radiation source heating. This prevents the write element from contacting the media during high-power HAMR operations, maintaining write operation reliability even at elevated radiation powers.
Solution Approach 2:
The patent applies preliminary anti-action by pre-compensating for thermal expansion effects before they cause write element contact. The slider body design and control mechanisms anticipate and counteract heating-induced dimensional changes, preventing contact before it occurs during high-power HAMR operations.
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 effectively maintains stable flying height during long use cycles by detecting temperature changes and adjusting the slider position, preventing write element slider-media contact and reducing data imprint errors.
Implementation Method 1
A tightly confined, high power laser light spot is used to heat a portion of the recording media to substantially reduce the coercivity of the heated portion
Implementation Method 2
locally heating a recording media to reduce the coercivity of the media so that an applied magnetic writing field can more easily direct the magnetization of the media during the temporary magnetic softening of the media caused by the heat source
Implementation Method 3
This heating causes a distortion of the slider shape, which leads to flying height changes
Implementation Method 4
a temperature sensor positioned a first distance from the radiation source submount, the first distance being between 5 nm and 100 nm
Data Source
AI summary
Embodiments described herein generally relate to controlling the flying height of a slider. The methods can include transmitting radiation from a radiation source, determining a change in temperature, the change in temperature being the difference between a first temperature and an ambient temperature and changing the flying height of the slider and head based on the change in temperature. The devices generally include a head with a supporting surface and a media facing surface, a radiation source submount, a radiation source, and a temperature sensor positioned proximate the radiation source submount or the radiation source.