Fly Height Actuator Calibration for Heat Assisted Magnetic Recording
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional disk drives face challenges in determining the appropriate dynamic fly height setting for the head to ensure optimal recording reliability, as excessive laser power can lead to data erasure or under-saturation, and existing methods for calibrating fly height settings are not effective in maintaining consistent fly height during write and read operations.
Innovation Solution
A method is developed to calibrate the laser power and generate a fly height actuation setting based on the calibrated laser power, using a closed-loop feedback system to maintain a target fly height during write operations and an open-loop system during read operations, with adjustments made to the fly height actuation setting to compensate for the heating effect of the laser, ensuring optimal recording quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If laser power is increased to improve recording quality, then magnetic field penetration improves, but data erasure or under-saturation occurs
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the fly height based on laser power settings. Different laser powers require different optimal fly heights to prevent data erasure while maintaining recording quality. The system establishes a relationship between laser power parameters and corresponding fly height parameters to optimize recording conditions.
Solution Approach 2:
The patent implements feedback through calibration procedures that determine optimal fly height actuator settings based on measured laser power. The system uses feedback from laser power calibration to adjust fly height actuator settings, creating a closed-loop control mechanism that prevents data erasure while maintaining recording reliability.
2Measurement precision
If fly height is decreased to improve signal quality, then recording sensitivity improves, but head-disk contact risk increases
Solution Approach 1:
The patent applies dynamics by using a dynamic fly height actuator that can adjust the head's fly height in real-time based on operating conditions. Rather than using a fixed fly height, the system dynamically modifies the fly height actuator setting according to laser power calibration results, allowing optimal signal quality while preventing head-disk contact.
3Ease of manufacture
If conventional fly height calibration methods are used, then manufacturing simplicity is maintained, but recording reliability deteriorates
Solution Approach 1:
The patent applies preliminary action by performing laser power calibration and determining optimal fly height actuator settings during the manufacturing or initialization phase. This preliminary calibration establishes the correct relationship between laser power and fly height before actual recording operations begin, ensuring recording reliability without adding complexity to the manufacturing process.
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 ensures consistent fly height control, improving recording reliability by adjusting the fly height actuation setting based on calibrated laser power, thereby enhancing data quality and preventing data erasure or under-saturation during write operations.
Implementation Method 1
heating the disk surface with a laser during write operations in order to decrease the coercivity of the magnetic medium
Implementation Method 2
a heater which controls fly height through thermal expansion
Data Source
AI summary
A disk drive is disclosed comprising a disk, a head comprising a laser operable to heat the disk while writing data to the disk, and a fly height actuator (FHA) operable to actuate the head vertically over the disk. A laser power applied to the laser during a write operation is calibrated, and a FHA write setting is generated for the FHA as a function of the calibrated laser power.