HAMR Laser Pulse Generator Timing Control
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Solution Overview
Problem
High-density magnetic storage systems face challenges in maintaining data stability due to thermal susceptibility, as grain size reduction increases susceptibility to thermally-induced decay, and conventional write heads cannot provide sufficient ferromagnetic anisotropy for stable recording.
Innovation Solution
The implementation of a heat-assisted magnetic recording (HAMR) system that uses a triggerable HAMR laser pulse generator to heat the magnetic medium near the Curie point, aligning laser and magnetic write-precompensation signals to enhance data stability and recording density, with a variable delay element controlling the phasing between laser pulses and magnetic write data signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If grain size is reduced to increase recording density, then recording density is improved, but data stability deteriorates due to increased susceptibility to thermal decay
Solution Approach 1:
The patent applies parameter changes by heating the magnetic medium to near the Curie point using a laser during the write process. This temporary change in temperature parameter reduces the ferromagnetic anisotropy, allowing the write head to magnetize smaller grains that would otherwise be too stable to write. After cooling, the grains maintain their magnetization with high thermal stability, thus achieving both high recording density and data stability.
Solution Approach 2:
The patent employs periodic action through pulsed laser heating that occurs only during the write operation. The laser is activated in periodic pulses synchronized with the write process, temporarily reducing the Curie temperature to enable magnetization of small grains. This periodic thermal assistance allows high-density recording without compromising the thermal stability of stored data during normal operation.
2Reliability
If ferromagnetic anisotropy is increased to improve data stability, then data stability is improved, but writeability deteriorates due to insufficient write head field strength
Solution Approach 1:
The patent changes the temperature parameter of the magnetic medium during writing by heating it to near the Curie point. This temporary parameter change reduces the ferromagnetic anisotropy and coercivity, enabling the write head to magnetize the medium with its limited field strength. The medium is then cooled to restore high anisotropy for stable data storage, thus resolving the contradiction between writeability and data stability.
Solution Approach 2:
The patent applies preliminary action by pre-heating the magnetic medium to near the Curie point before applying the write field. This preliminary thermal treatment softens the magnetic properties of the medium, making it easier to magnetize with the available write head field strength. After writing, the medium cools and regains its high anisotropy for stable storage, thus enabling writing to high-anisotropy media with conventional write heads.
3Device complexity
If laser pulse timing is not precisely aligned with magnetic write signal, then device complexity is reduced, but manufacturing precision deteriorates due to misalignment between heating and writing processes
Solution Approach 1:
The patent employs feedback mechanisms to precisely control the timing and synchronization of the laser pulse with the magnetic write signal. By monitoring the relative timing and adjusting the laser pulse duration and positioning accordingly, the system achieves accurate spatial alignment between the heated region and the written data bits. This feedback control ensures optimal writing conditions while maintaining manageable device complexity through automated timing adjustment.
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 improves data stability and recording density by reducing thermal decay and enabling the use of limited write head field strength, maintaining correlation between laser pulses and data bits, thus enhancing the longevity and readability of recorded data in high-density magnetic storage systems.
Implementation Method 1
heats the magnetic medium in the vicinity of a written data bit to near the Curie point using a laser
Implementation Method 2
heats the magnetic medium in the vicinity of a written data bit to near the Curie point
Implementation Method 3
Data to be recorded is provided to the write head as an alternating electrical current. The electrical current passes through a metallic coil in the write head, generating a magnetic field.
Implementation Method 4
The magnetization state of a pole tip in the write head is switched by the magnetic field. As the magnetized pole tip is passed over the magnetic medium, the magnetization of regions of the magnetic medium adjacent the pole tip is altered
Data Source
Figure 1
Figure 2~4
Figure 3A~3B
AI summary
Various embodiments of the present invention provide apparatuses, systems and methods for heat assisted magnetic recording. For example, an apparatus is disclosed that includes a signal generator operable to generate laser trigger pulses (240) at the transition rate of the magnetic write data signal (216), a variable delay element (446) operable to control an alignment between the laser pulse control signal (240) and the magnetic write data signal (216), a phase difference detector (262) operable to control the variable delay element (446), a triggerable pulse generator circuit operable to generate a laser pulse control signal (264) based on the laser trigger pulses (240), a magnetic write head (232) operable to record data to a magnetic storage medium under control of the magnetic write data signal (216), and a laser diode (242) operable to heat the magnetic storage medium under control of the laser pulse control signal (264).