HAMR Write Pole Pre-Heating for Stable Head-Media Spacing
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Solution Overview
Problem
Conventional heat-assisted magnetic recording (HAMR) technologies face challenges with inconsistent read and write reliability due to thermal expansion of HAMR heads, causing fluctuations in the distance between the media and the head, which affects signal strength and recording density.
Innovation Solution
A heating device is positioned between the write pole and the near field transducer, pre-heating the write pole and deactivating it during writing operations to maintain a constant spacing between the media-facing side of the head and the magnetic medium, using a combination of a write pole, near field transducer, and waveguide to achieve stable thermal control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If HAMR heads are heated to enable heat-assisted magnetic recording, then recording density is improved, but thermal expansion causes fluctuation in head-media spacing and inconsistent read/write reliability
Solution Approach 1:
The patent applies preliminary action by pre-heating the write pole before the actual writing operation. The heating device is activated in advance to raise the temperature of the write pole, causing thermal expansion that pre-establishes the optimal head-media spacing. This preliminary thermal preparation ensures that when writing occurs, the spacing is already stabilized, preventing fluctuations during the recording process and improving reliability.
Solution Approach 2:
The patent implements dynamics by making the head-media spacing adjustable through controlled thermal expansion. The heating device allows the write pole to dynamically change its dimensions based on temperature, enabling the system to adapt the spacing to optimal values during operation. This dynamic adjustment resolves the contradiction by allowing high recording density through controlled expansion while maintaining stable spacing for reliable read/write operations.
2Temperature
If the distance between media and head fluctuates due to thermal expansion, then thermal effects are reduced, but signal strength becomes inconsistent
Solution Approach 1:
The patent applies feedback by incorporating a sensor that continuously monitors the head-media spacing and provides signals to a controller. The controller uses this feedback information to adjust the heating device's power output, maintaining optimal spacing despite thermal effects. This closed-loop control ensures consistent signal strength while allowing thermal management for high recording density.
Solution Approach 2:
The patent implements parameter changes by actively controlling the temperature of the write pole through the heating device. By adjusting the thermal parameter, the system optimizes the magnetic properties and spacing for consistent signal generation. This controlled parameter change resolves the contradiction between thermal management for density and signal consistency.
3Productivity
If miniaturization of magnetic grains is pursued to increase capacity, then recording density is improved, but noise performance and spatial resolution deteriorate
Solution Approach 1:
The patent applies parameter changes by using thermal energy to alter the magnetic properties of the grains during writing. Heating reduces the coercivity of the magnetic grains, enabling stable writing even at extremely small grain sizes. This thermal parameter change allows miniaturization for higher capacity while maintaining noise performance through controlled thermal effects that stabilize the magnetic state.
Solution Approach 2:
The patent utilizes phase transitions by leveraging the temperature-dependent magnetic properties of the recording medium. The heating process induces a temporary phase change in the magnetic grain properties, transitioning from a high-coercivity state to a low-coercivity state for writing, then back to the original state for stable storage. This phase transition mechanism enables miniaturization while maintaining signal integrity.
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 consistent head-media spacing, improving read and write reliability by maintaining a stable thermal profile and reducing thermal fluctuations, thereby enhancing recording density and data bit size in HAMR systems.
Implementation Method 1
Heating of the media surface has been accomplished by a number of techniques such as focused laser beams or near field optical sources. However, these techniques for heating the media surface during HAMR recording also cause the temperature of the HAMR heads themselves to increase, thereby inducing thermal expansion.
Implementation Method 2
HAMR recording employs heat to lower the effective coercivity of a localized region on the magnetic media surface and write data within this heated region. The data state becomes stored, or 'fixed,' upon cooling the media to ambient temperatures.
Implementation Method 3
A heating device is positioned between the write pole and at least one of the waveguide and the near field transducer
Data Source
AI summary
In one general embodiment, an apparatus includes a write pole, a near field transducer, a waveguide for delivering light to the near field transducer, and a first heating device positioned between the write pole and at least one of the waveguide and the near field transducer.