HAMR Head Laser Smoothing for Lubricant Layer Uniformity
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Solution Overview
Problem
In heat-assisted magnetic recording, the temperature fluctuations in the lubricant layer of the magnetic recording medium cause unevenness, leading to signal quality deterioration and head operation failures due to fluctuations in flying height and smearing.
Innovation Solution
A control method for a heat-assisted magnetic recording and reproduction device that performs a smoothing process on the lubricant layer using a heat-assisted magnetic recording head with a second laser current value lower than the first, irradiating near-field light to reduce surface unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heat-assisted magnetic recording is performed using near-field light to raise the temperature of the magnetic recording medium to the Curie temperature for recording, then recording capability is improved, but the lubricant layer becomes uneven due to temperature differences between the data area and servo area, causing signal quality deterioration and head operation failure
Solution Approach 1:
The patent applies a preliminary smoothing action to the lubricant layer before heat-assisted magnetic recording operations. The control unit performs a smoothing process that moves the lubricant in the data area to a predetermined position, preventing the formation of steps and unevenness that would otherwise occur during subsequent high-temperature recording operations. This preliminary action ensures lubricant layer uniformity is maintained throughout the recording process.
Solution Approach 2:
The patent changes the positional parameter of the lubricant layer by applying a smoothing process that actively moves lubricant molecules to predetermined positions in the data area. This parameter change (positioning) compensates for the temperature-induced lubricant migration that occurs during heat-assisted recording, thereby maintaining lubricant layer uniformity across different operational temperature states.
2Temperature
If the temperature of the lubricant layer rises in the data area during recording, then magnetic recording becomes feasible, but the lubricant becomes more mobile and forms steps, deteriorating signal quality
Solution Approach 1:
The patent applies local quality control by distinguishing between different areas of the magnetic recording medium. The smoothing process specifically targets the data area where temperature rise and lubricant migration occur during recording, while leaving the servo area unaffected. This localized approach addresses the signal quality issue in the data area without interfering with servo functionality.
Solution Approach 2:
The smoothing process is performed as a preliminary action before recording operations that would cause temperature rise. By pre-positioning the lubricant in the data area to predetermined positions, the system prevents the formation of steps and unevenness that would otherwise occur when the lubricant becomes mobile during high-temperature recording, thereby maintaining signal quality.
3Ease of operation
If the lubricant layer becomes uneven with steps of several angstroms between data area and servo area, then head operation may fail due to smearing, but no simple solution exists to maintain lubricant uniformity during heat-assisted recording
Solution Approach 1:
The patent implements a feedback mechanism where the control unit monitors and manages the lubricant layer state. The smoothing process is controlled based on the operational requirements, and the system continuously maintains lubricant uniformity by applying corrective positioning actions. This feedback control ensures head operation reliability by preventing lubricant unevenness that would cause smearing and operation failures.
Solution Approach 2:
The smoothing process enables the lubricant layer to self-correct its unevenness. By applying controlled movements that relocate lubricant to predetermined positions, the system allows the lubricant layer to maintain its own uniformity without requiring external mechanical intervention or complex structural modifications to the head or medium.
Data Source
AI summary
According to an embodiment, a control method for a heat-assisted magnetic recording and reproducing device including a heat-assisted magnetic recording head including a main pole, a near-field transducer generating near-field light, a waveguide propagating light to the near-field transducer, and a laser light source supplying light to the waveguide, and a heat-assisted magnetic recording medium that has a lubricant layer on a recording surface opposing the head, includes irradiating the near-field light on the medium with a second laser current value set lower than a first laser current value at a time of write, and operating the head, thereby performing a smoothing process on the surface of the lubricant layer.