NFT Contamination Detection via Thermal Gradient Monitoring
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Solution Overview
Problem
Data storage devices face reliability issues due to contamination of the near field transducer (NFT) during write operations, which can lead to thermal degradation and degradation of the head/disk interface, affecting recording quality and reliability.
Innovation Solution
The solution involves detecting contamination of the NFT by measuring changes in the thermal gradient and magnetic write width, and confirming the detection through further measurements at multiple power settings or by assessing the offset between the write and read elements, allowing for remedial actions such as warning or burnishing procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If HAMR write operations are performed with high laser power to achieve target magnetic write width, then recording quality is improved, but NFT thermal degradation and contamination occur
Solution Approach 1:
The system performs preliminary detection of thermal gradient and magnetic write width before contamination causes damage. By continuously monitoring these parameters during write operations, the system can identify degradation trends early and trigger remedial actions before the NFT fails completely.
Solution Approach 2:
The system implements feedback control by monitoring thermal gradient and magnetic write width parameters, comparing them against threshold values, and adjusting operations accordingly. When contamination is detected through parameter changes, the system provides feedback to trigger burnishing procedures or write operation cancellations.
2Manufacturing precision
If laser power is increased to compensate for NFT contamination, then magnetic write width is maintained, but thermal degradation of NFT accelerates
Solution Approach 1:
The system continuously monitors thermal gradient and magnetic write width parameters. When contamination is detected through parameter changes, the feedback mechanism triggers remedial actions such as burnishing procedures or write operation cancellations, preventing further thermal degradation from compensatory laser power increases.
Solution Approach 2:
The system prepares for thermal degradation by detecting early signs of contamination through thermal gradient and magnetic write width measurements. By triggering preventive burnishing procedures before severe thermal damage occurs, the system cushions against the harmful effects of continued high-power laser operation.
3Measurement precision
If continuous monitoring of thermal gradient is implemented, then contamination detection accuracy is improved, but system complexity increases
Solution Approach 1:
The thermal gradient monitoring system serves multiple functions: it detects NFT contamination, monitors write operation quality, and triggers preventive maintenance procedures. By making the monitoring system multi-functional, the patent reduces overall system complexity while maintaining high detection accuracy.
Solution Approach 2:
The system merges thermal gradient monitoring with existing write operation control and read signal processing functions. By combining these monitoring functions into integrated control logic, the patent reduces device complexity while maintaining comprehensive contamination detection capability.
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 effectively detects and addresses NFT contamination, preventing thermal degradation and maintaining recording reliability by enabling timely intervention and maintaining the integrity of the head/disk interface.
Implementation Method 1
Heat assisted magnetic recording (HAMR) is a recent development that improves the quality of written data by heating the disk surface during write operations in order to decrease the coercivity of the magnetic medium
Implementation Method 2
The magnetic field generated by the write coil to more readily magnetize the disk surface
Implementation Method 3
the magnetic transitions are sensed by a read element (e.g., a magneto-resistive element) and the resulting read signal demodulated
Data Source
AI summary
A data storage device is disclosed comprising a head actuated over a magnetic media, wherein the head comprises a write element, a read element, a laser, and a near field transducer. An operating thermal gradient of the magnetic media is periodically measured at an operating power setting for the laser that achieves a target magnetic write width. When a slope of the operating thermal gradient exceeds a threshold, a test thermal gradient and magnetic write width of the magnetic media is measured at multiple power settings for the laser in order to detect a contamination of the near field transducer.