TMR Head Magnetic Tape Surface Roughness and Cluster Ratio
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Solution Overview
Problem
Magnetic tape devices face challenges in achieving high signal-to-noise ratio (SNR) and preventing significant decreases in resistance value of tunnel magnetoresistive (TMR) heads due to increased recording density and surface smoothness of magnetic tapes, leading to reduced reproduction output.
Innovation Solution
A magnetic tape device with a TMR head using a magnetic tape featuring a non-magnetic support, a magnetic layer with ferromagnetic powder and a binding agent, and specific surface roughness and magnetic cluster area ratios, which prevents significant decreases in resistance value and maintains high SNR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If recording density of magnetic recording medium is increased, then recording capacity is improved, but magnetic signal strength becomes weak
Solution Approach 1:
The patent changes the magnetic properties of the recording medium by controlling particle size distribution, saturation magnetization, and coercivity of the magnetic particles. These parameter changes enable high recording density while maintaining sufficient magnetic signal strength for reliable reproduction.
Solution Approach 2:
The patent uses composite magnetic layers combining different magnetic particles with specific properties. This composite structure allows optimization of both recording density and signal strength by leveraging the complementary characteristics of different magnetic materials.
2Measurement precision
If TMR head is used for high-density recording, then sensitivity is improved, but resistance value decreases significantly
Solution Approach 1:
The patent modifies the magnetic parameters of the recording medium, specifically reducing maximum coercivity and adjusting saturation magnetization. These changes reduce the magnetic field strength required for recording, preventing excessive magnetization that would cause TMR head resistance to decrease significantly.
Solution Approach 2:
The patent establishes feedback control by monitoring TMR head resistance during operation and adjusting recording conditions accordingly. This prevents resistance drift by maintaining optimal magnetic field parameters that preserve head characteristics.
3Measurement precision
If surface smoothness of magnetic layer is increased, then SNR is improved, but reproduction output decreases over time
Solution Approach 1:
The patent optimizes surface roughness parameters within a specific range rather than maximizing smoothness. This balanced approach maintains low noise while preventing the conditions that lead to reproduction output degradation over time.
Solution Approach 2:
The patent applies different surface quality characteristics to different regions or aspects of the magnetic layer. The surface has controlled roughness features that provide low noise while maintaining structural properties that prevent degradation during repeated use.
4Quantity of substance
If magnetic particles are aggregated, then recording density is improved, but magnetic signal becomes weak
Solution Approach 1:
The patent controls the size distribution and spatial arrangement of magnetic particles to achieve optimal packing density without excessive aggregation. This maintains high recording density while preserving sufficient magnetic signal strength through proper particle dispersion and orientation.
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
The solution enables high-sensitivity reproduction of information at high linear recording densities with reduced noise, preventing significant decreases in TMR head resistance values and ensuring stable reproduction output over time.
Implementation Method 1
a magnetic head (hereinafter, also referred to as a 'TMR head') including a tunnel magnetoresistance effect type element (hereinafter, also referred to as a 'TMR element') as a reproducing element
Implementation Method 2
a magnetic layer including ferromagnetic powder and a binding agent on the non-magnetic support
Data Source
AI summary
A magnetic tape device includes a magnetic tape; and a reproducing head, in which the reproducing head is a Tunneling Magnetoresistive (TMR) head, the center line average surface roughness Ra measured regarding the surface of the magnetic layer of the magnetic tape is equal to or smaller than 2.0 nm, the logarithmic decrement acquired by a pendulum viscoelasticity test performed regarding the surface of the magnetic layer is equal to or smaller than 0.050, and the ratio (Sdc/Sac) of an average area Sdc of a magnetic cluster of the magnetic tape in a DC demagnetization state and an average area Sac of a magnetic cluster of the magnetic tape in an AC demagnetization state measured with a magnetic force microscope is 0.80 to 1.30.