Magnetic Recording Device Asymmetric Write Current Control
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Solution Overview
Problem
In magnetic recording devices, the intensity of the recording magnetic field is limited, restricting the coercive force of the recording medium, which affects thermal stability and information recording, especially when using microwave assisted recording methods, where asymmetric microwave frequencies can reduce signal quality due to mismatched polarities.
Innovation Solution
A magnetic recording device that adjusts the write current for each polarity to ensure identical microwave frequencies in positive and negative magnetic fields, optimizing the microwave frequency for the recording medium and maximizing the microwave assisted effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a strong high frequency magnetic field is applied to reduce the magnetic reversal field intensity, then the coercive force reduction effect is improved, but the device complexity and control difficulty increase due to the need for precise frequency matching
Solution Approach 1:
The patent applies feedback control by detecting the actual microwave frequency generated by the spin-torque oscillator and adjusting the write current accordingly. The frequency detection unit measures the microwave frequency, and the control unit modifies the write current to maintain the microwave frequency at the optimal resonance frequency of the recording medium, ensuring reliable coercive force reduction while simplifying the control mechanism through automatic adjustment.
Solution Approach 2:
The patent changes the write current parameter asymmetrically for positive and negative polarities to compensate for frequency shifts. By adjusting the magnitude of the write current based on the polarity, the system maintains optimal microwave frequency alignment with the recording medium's resonance frequency, achieving reliable recording without increasing device complexity.
2Measurement precision
If asymmetric write currents are applied to correct frequency shifts, then the signal quality is improved, but the device complexity increases due to additional control mechanisms
Solution Approach 1:
The control unit performs multiple functions: it detects the microwave frequency, determines the polarity of the write current, calculates the appropriate current adjustment, and applies the corrected write current. By consolidating these functions into a single control unit, the patent improves signal quality through asymmetric write current adjustment while minimizing the increase in device complexity through functional integration.
Solution Approach 2:
The system uses its own write current to generate the microwave frequency that it then adjusts. The spin-torque oscillator generates microwaves based on the write current applied to the main magnetic pole, and the control unit uses this self-generated signal for frequency detection and adjustment, eliminating the need for external frequency reference devices and reducing overall system complexity.
3Measurement precision
If the microwave frequency is optimized for one polarity, then the recording quality for that polarity is improved, but the recording quality for the opposite polarity deteriorates due to frequency mismatch
Solution Approach 1:
The patent deliberately applies asymmetric write currents for positive and negative polarities. The magnitude of the write current is adjusted differently for each polarity to compensate for the asymmetric frequency characteristics of the spin-torque oscillator. This asymmetric approach ensures that the microwave frequency generated during recording matches the resonance frequency of the recording medium for both polarities, maintaining high recording quality across all recording conditions.
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 adjustment enhances the signal-to-noise ratio by ensuring optimal microwave frequencies for both polarities, thereby improving recording quality and stability.
Implementation Method 1
a frequency of the microwave magnetic field corresponds to a magnetic resonance frequency of a recording medium... a coercive force of magnetization of a medium is considerably reduced by ferromagnetic resonance of the microwave magnetic field and the magnetization of the medium
Implementation Method 2
spin-torque oscillator that is free of a bias magnetic field from the outside... a spin-torque oscillator that controls a rotational direction of an FGL with use of a magnetic field of a main magnetic pole adjacent to the FGL
Implementation Method 3
generating a microwave (high frequency magnetic field)... a magnetic head magnetic field
Implementation Method 4
recording information while locally reducing the coercive force of the recording medium with use of a high frequency magnetic field as a recording magnetic field from a recording head... subjecting the magnetic recording medium to joule heating or magnetic resonance heating
Implementation Method 5
subjecting the magnetic recording medium to joule heating or magnetic resonance heating by means of a high frequency magnetic field
Data Source
AI summary
In a magnetic recording device adopting a microwave assisted recording method, a microwave frequency on a positive polarity side and a microwave frequency on a negative polarity side are adjusted to be optimal.The magnetic recording device of the invention supplies to a magnetic head a write current of which a current waveform on the positive polarity side and a current waveform on the negative polarity side are asymmetric.