Laser Power Staging Register for HAMR Transient Avoidance
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Solution Overview
Problem
In data storage devices, adjusting laser power during write operations can cause transients in recorded data, making it unrecoverable, especially due to self-heating effects that vary the output power, which existing technologies struggle to manage without compromising recording quality.
Innovation Solution
The implementation of a staging and operating register system for the laser power settings allows for updates during non-write modes, such as inter-sector gaps or servo sector reading, ensuring that the laser power is adjusted without causing transients in the data by transferring the updated power settings from a staging register to an operating register during non-write intervals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If laser power is adjusted during write operations, then recording quality can be maintained despite self-heating effects, but data transients occur making the recorded data unrecoverable
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing compensation values in a lookup table before write operations occur. The system anticipates self-heating effects and prepares corrective laser power adjustments in advance, selecting appropriate compensation values based on expected write operation characteristics (duration, power level) before actual writing begins. This allows the system to maintain recording quality without causing data transients during the actual write operation.
2Reliability
If laser power is kept constant during write operations, then data transients are avoided, but recording quality deteriorates due to self-heating effects varying the output power
Solution Approach 1:
The patent implements feedback by continuously monitoring write operation characteristics (duration, power level, inter-sector gap) and using this information to select appropriate compensation values from a pre-populated lookup table. The system measures actual write parameters and adjusts laser power compensation accordingly, creating a closed-loop control system that maintains recording quality while avoiding data transients. The lookup table stores pre-calculated compensation values that are selected based on real-time feedback from the write operation parameters.
3Manufacturing precision
If laser power adjustments are made during write operations, then recording quality is maintained, but the system complexity increases due to need for real-time power management
Solution Approach 1:
The patent reduces system complexity by performing all complex calculations and compensation value determinations in advance, before write operations begin. A lookup table is pre-populated with compensation values for various write operation scenarios (different durations, power levels, inter-sector gaps). During actual write operations, the system simply queries this pre-computed table and applies the appropriate compensation, avoiding the need for complex real-time calculations and reducing computational burden during time-critical write operations.
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 maintains target recording quality by avoiding data transients during write operations, allowing for dynamic power adjustments without rendering data sectors unrecoverable, thus enhancing the reliability and stability of data storage.
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
modulating a write current in an inductive coil to record magnetic transitions onto the disk surface
Implementation Method 3
the magnetic transitions are sensed by a read element (e.g., a magnetoresistive element)
Data Source
AI summary
A data storage device is disclosed comprising a head actuated over a disk, wherein the head comprises a laser configured to heat the disk while writing data to the disk. While writing data to the disk, an updated power setting for the laser is stored in a staging register, and during a non-write mode, the updated power setting is transferred from the staging register to an operating register in order to update an operating power for the laser.