Spin-Torque Oscillator Reproducing Head Asymmetric Shielding
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Solution Overview
Problem
Conventional magnetoresistance effect sensors face challenges in maintaining a practical signal-to-noise ratio due to increasing thermal mag-noise and inter-bit interference noise as magnetic recording density increases, limiting the reduction of inter-bit interference noise in magnetic recording and reproducing systems.
Innovation Solution
A magnetic reproducing head with a spin-torque oscillator and a pair of shield parts is designed, where the spin-torque oscillator is positioned between the shield parts, with the distance between the shield parts and the magnetic recording medium being shorter than the distance between the spin-torque oscillator and the medium, allowing effective absorption of magnetic fields from adjacent bits and enhanced detection of the target bit's magnetic field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the size of magnetic sensor is decreased to match the medium bit size, then the recording density is improved, but the signal-to-noise ratio deteriorates due to increased thermal mag-noise and inter-bit interference noise
Solution Approach 1:
The patent applies local quality by creating an asymmetric shield configuration where the first shield is positioned closer to the magnetic recording medium than the second shield. This asymmetric arrangement optimizes the local magnetic field environment around the spin-torque oscillator, enhancing signal detection while suppressing inter-bit interference noise. The differential shielding approach creates a localized favorable magnetic environment that improves signal-to-noise ratio without requiring larger sensor dimensions.
2Measurement precision
If magnetic shields are provided to suppress inter-bit interference noise, then the signal quality is improved, but the gap between shields cannot be smaller than the thickness of the multilayered film, limiting the suppression effectiveness
Solution Approach 1:
The patent implements asymmetry in the shield structure by positioning the first shield at a different distance from the magnetic recording medium compared to the second shield. Specifically, the first shield is placed closer to the medium, creating an asymmetric magnetic shielding configuration. This asymmetric arrangement allows optimized suppression of inter-bit interference noise while accommodating the multilayered film thickness constraint, as the shields are arranged to provide effective shielding without requiring symmetric spacing.
3Object-affected harmful factors
If the gap between magnetic shields is decreased to handle smaller medium bit size, then the inter-bit interference suppression is improved, but the gap cannot be smaller than the magnetic sensor thickness
Solution Approach 1:
The patent applies local quality by creating an asymmetric shield configuration where the first shield is positioned closer to the magnetic recording medium than the second shield. This asymmetric arrangement optimizes the local magnetic field environment around the spin-torque oscillator, enhancing signal detection while suppressing inter-bit interference noise. The differential shielding approach creates a localized favorable magnetic environment that improves signal-to-noise ratio without requiring larger sensor dimensions.
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 configuration reduces inter-bit interference noise in the reproduced signal by selectively detecting the magnetic field from the target bit, enabling efficient information retrieval with improved signal quality even at higher recording densities.
Implementation Method 1
a spin-torque oscillator magnetic sensor using the spin transfer effect has been proposed
Implementation Method 2
The inter-bit interference noise may be suppressed by forming magnetic shields so as to absorb magnetic fields from medium bits other than a target bit
Data Source
AI summary
According to one embodiment, a reproducing head includes a spin-torque oscillator and a pair of shield parts. The spin-torque oscillator has a first surface facing a magnetic recording medium. The pair of shield parts each has a second surface facing the magnetic recording medium, the spin-torque oscillator being arranged between the shield parts. A distance between the second surface and the magnetic recording medium is shorter than a distance between the first surface and the magnetic recording medium.