Magnetic Tape Head Tracking Servo via TMR Resistance Control
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Solution Overview
Problem
The challenge in magnetic tape devices is to maintain high sensitivity for reading weak magnetic signals, particularly when using TMR heads as servo heads, due to a significant decrease in resistance value, which affects the accuracy of head tracking servo and signal-to-noise ratio (SNR) during the reading of servo patterns on magnetic tapes with high surface smoothness.
Innovation Solution
A magnetic tape device with a TMR head using a magnetic layer comprising ferromagnetic hexagonal ferrite powder, fatty acid, and fatty acid amide, where the magnetic layer has a specific X-ray diffraction intensity ratio, surface roughness, and C—H derived C concentration, preventing a significant decrease in resistance value and enhancing SNR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If TMR head is used as servo head for reading servo patterns, then sensitivity for reading weak magnetic signals is improved, but resistance value decreases significantly affecting head tracking servo accuracy
Solution Approach 1:
The patent changes the physical and chemical parameters of the magnetic layer by controlling the XRD intensity ratio (Int(110)/Int(114)) to be 0.5 to 4.0, vertical direction squareness ratio to be 0.65 to 1.00, and surface roughness Ra to be 2.0 nm or less. These parameter changes optimize the magnetic layer properties to prevent significant resistance value decrease in TMR heads during servo pattern reading, thereby maintaining both high sensitivity and reliable head tracking servo accuracy
Solution Approach 2:
The patent uses a composite magnetic layer containing ferromagnetic hexagonal ferrite powder, binding agent, and lubricant components. This composite material structure provides both the magnetic properties needed for high-sensitivity signal reading and the surface characteristics that prevent TMR head resistance degradation, resolving the contradiction between sensitivity and reliability
2Measurement precision
If magnetic layer surface roughness is reduced to enhance SNR, then signal-to-noise ratio is improved, but head tracking servo accuracy is affected due to resistance value decrease
Solution Approach 1:
The patent optimizes the surface roughness parameter Ra to be 2.0 nm or less, which enhances the signal-to-noise ratio by improving magnetic signal readability. Simultaneously, the controlled XRD intensity ratio and squareness ratio ensure that the magnetic layer maintains properties that prevent significant resistance value decrease in TMR heads, thereby maintaining head tracking servo accuracy despite the reduced surface roughness
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 effectively prevents a significant decrease in resistance value and improves the signal-to-noise ratio, ensuring accurate head tracking servo and high-capacity data recording on magnetic tapes.
Implementation Method 1
the servo head is a magnetic head including a tunnel magnetoresistance effect type element as a servo pattern reading element
Implementation Method 2
the magnetic layer includes ferromagnetic powder and a binding agent on the non-magnetic support
Data Source
AI summary
The magnetic tape device includes a magnetic tape including a magnetic layer, in which an intensity ratio of a peak intensity of a diffraction peak of a (110) plane with respect to a peak intensity of a diffraction peak of a (114) plane of a hexagonal ferrite crystal structure obtained by an X-ray diffraction analysis of the magnetic layer by using an In-Plane method is 0.5 to 4.0, a vertical direction squareness ratio of the magnetic tape is 0.65 to 1.00, Ra measured regarding a surface of the magnetic layer is equal to or smaller than 2.0 nm, and a C—H derived C concentration calculated from a C—H peak area ratio of C1s spectra obtained by X-ray photoelectron spectroscopic analysis performed on the surface of the magnetic layer at a photoelectron take-off angle of 10 degrees is 45 to 65 atom %.