Actuator Crash Stop Calibration for Write Parameter Accuracy
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Solution Overview
Problem
Current data storage devices face challenges in accurately positioning heads over disk surfaces due to limitations in servo sector information and write parameter optimization, which can lead to errors and potential damage during write operations.
Innovation Solution
The implementation of a control circuitry that configures write parameters by writing and reading bursts with different settings while the actuator arm is pressed against a crash stop, using a laser and near field transducer to heat the disk, and adjusting write parameters based on quality metrics to ensure precise head positioning and prevent overshooting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the actuator arm is pressed against a crash stop to calibrate write parameters, then write parameter accuracy is improved, but the risk of mechanical damage to the write head increases
Solution Approach 1:
The system performs a preliminary detection action by reading back test bursts written at the crash stop position before actually writing user data. This preliminary measurement of quality metrics allows the system to identify optimal write parameters and detect potential issues before they cause damage during normal operation
Solution Approach 2:
The system implements feedback by reading back the test bursts and measuring quality metrics to determine optimal write parameters. This feedback loop allows the system to adjust write current, laser power, and other parameters based on actual performance measurements, thereby improving write accuracy while preventing damage through continuous monitoring
2Manufacturing precision
If HAMR or MAMR techniques are used to improve write quality, then data storage quality is improved, but the complexity of the write head assembly increases
Solution Approach 1:
The patent combines multiple write assist technologies (HAMR laser diode and MAMR spin torque oscillator) into a single integrated write head assembly. This merging approach allows the system to leverage both heating and magnetic field techniques simultaneously, improving write quality while managing complexity through integration rather than separate components
Solution Approach 2:
The system dynamically adjusts write parameters including laser power, write current, and spin torque oscillator frequency based on measured quality metrics from test bursts. This parameter optimization allows the system to achieve high data storage quality by tuning the interaction between thermal and magnetic fields rather than relying on fixed complex hardware configurations
3Measurement precision
If servo sector information is used for head positioning, then positioning accuracy is improved, but the system cannot operate without pre-recorded servo data
Solution Approach 1:
The system performs preliminary calibration by writing and reading test bursts at known positions (crash stop) before normal operation. This preliminary action establishes reference quality metrics and optimizes write parameters without requiring pre-existing servo data, enabling the system to operate in environments where servo sectors may not be available or reliable
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 enables accurate and safe configuration of write parameters, improving data storage quality by ensuring precise head positioning and preventing damage to write components, while allowing for efficient calibration of write settings without relying on initial servo information.
Implementation Method 1
heating the disk surface during write operations in order to decrease the coercivity of the magnetic medium
Implementation Method 2
fabricating a laser diode and a near field transducer (NFT) with other write components of the head
Implementation Method 3
using a spin torque oscillator (STO) to apply a high frequency auxiliary magnetic field to the media close to the resonant frequency of the magnetic grains
Implementation Method 4
close to the resonant frequency of the magnetic grains
Implementation Method 5
an actuator arm which is rotated about a pivot by a voice coil motor (VCM) to position the head radially over the disk
Implementation Method 6
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 disk surface by an actuator arm. The actuator is controlled to press the actuator arm against a crash stop in order to write a plurality of bursts on the disk surface each with a different write parameter setting. Each burst is read in order to measure a quality metric for each burst, and an operating setting for the write parameter is configured based on the measured quality metrics.