Thermally Assisted Magnetic Recording Head Laser Control
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Solution Overview
Problem
The increasing recording density of magnetic disks reduces the thermostability of remanent magnetization, and using ferromagnetic materials to improve anisotropy magnetic field intensity does not adequately support the maximum recording magnetic field, leading to insufficient magnetic fields for recording, which is addressed by the thermally assisted magnetic recording system that requires evaluation of coercive force variation for signal stability.
Innovation Solution
A magnetic disk device with a magnetic head, laser-beam-intensity control unit, reproduced-signal detecting unit, and magnetic-disk evaluating unit evaluates the signal quality by controlling the laser beam intensity and write current to manage coercive force and noise levels, optimizing the thermally assisted magnetic recording process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ferromagnetic material is used to improve anisotropy magnetic field intensity, then thermostability of remanent magnetization is improved, but maximum recording magnetic field becomes insufficient
Solution Approach 1:
The patent changes the physical state parameter by introducing thermal heating to modify the magnetic properties of the recording medium. By heating the magnetic disk locally, the coercive force decreases, allowing the magnetic head to generate sufficient magnetic field for recording even with high-anisotropy materials that would normally be too stable.
Solution Approach 2:
The patent introduces thermal energy as an intermediary to mediate between the magnetic head and the recording medium. The laser beam heats the magnetic disk, creating a temporary state where the magnetic properties allow recording, thus enabling the interaction between the magnetic head and the stable ferromagnetic material.
2Force
If laser beam intensity is increased to heat magnetic disk for thermally assisted recording, then coercive force decreases enabling recording, but signal quality deteriorates due to noise
Solution Approach 1:
The patent employs feedback control by measuring the reproduced signal and the laser beam intensity, then evaluating the noise level and signal-to-noise ratio. This feedback loop allows the system to optimize the laser intensity to achieve the right balance between reducing coercive force and maintaining signal quality.
Solution Approach 2:
The patent makes the laser beam intensity dynamic and adjustable rather than fixed. By controlling the intensity based on real-time signal evaluation and noise analysis, the system adapts the heating level to optimize both coercive force reduction and signal quality maintenance.
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 signal quality by evaluating and optimizing the coercive force and noise levels, ensuring high signal-to-noise ratio and identifying high, medium, and low-quality recording regions, enabling effective magnetic recording and reproduction.
Implementation Method 1
a laser beam is irradiated onto a magnetic disk so as to locally heat the magnetic disk
Implementation Method 2
locally heat the magnetic disk, such that the strength of a reversal magnetic field is reduced
Implementation Method 3
a magnetic field is generated in a region overlapping the heated region in the magnetic disk, so as to reverse a magnetization direction
Implementation Method 4
A magnetic head reads a signal recorded in the magnetic disk
Data Source
AI summary
A magnetic disk device of an embodiment includes a magnetic disk, a magnetic head, a laser-beam-intensity control unit, a reproduced-signal detecting unit, and a magnetic-disk evaluating unit. The magnetic head reads a signal recorded in the magnetic disk, or performs magnetic recording while irradiating a laser beam onto the magnetic disk. The laser-beam-intensity control unit controls the intensity of the laser beam. The reproduced-signal detecting unit detects the signal read by the magnetic head. The magnetic-disk evaluating unit evaluates the signal read from the magnetic head, on the basis of a relation between a noise level detected from the signal read by the magnetic head, and the intensity of the laser beam.