TMR Head Servo Tracking with Hexagonal Ferrite Tape
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Solution Overview
Problem
The challenge in magnetic tape devices is to maintain high signal-to-noise ratio (SNR) during servo pattern reading, which decreases due to the narrow read track width, leading to inaccuracies in head tracking servo, especially when using a TMR head as the servo head, where a significant decrease in resistance value occurs, affecting the sensitivity and accuracy of the magnetic head positioning.
Innovation Solution
A magnetic tape device with a TMR head using a magnetic layer with ferromagnetic hexagonal ferrite powder, a non-magnetic support, and a binding agent, optimized with specific surface roughness, XRD intensity ratio, and logarithmic decrement to prevent resistance value decreases, ensuring high SNR and accurate head tracking servo.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the read track width is narrowed to increase recording density, then the recording capacity is improved, but the signal-to-noise ratio during servo pattern reading deteriorates
Solution Approach 1:
The patent changes the physical and chemical parameters of the magnetic layer, specifically controlling the XRD intensity ratio (Int(110)/Int(114)) to be within 0.5 to 4.0 and the logarithmic decrement to be within 0.010 to 0.050. These parameter changes optimize the magnetic layer's properties to maintain high signal-to-noise ratio during servo pattern reading even with narrow read track width, thereby resolving the contradiction between increased recording capacity and maintained measurement precision
2Measurement precision
If the magnetic layer surface smoothness is increased to improve signal quality, then the signal-to-noise ratio is improved, but the resistance value of the TMR head decreases significantly
Solution Approach 1:
The patent optimizes the logarithmic decrement parameter of the magnetic layer to be within 0.010 to 0.050. This specific parameter control prevents significant resistance value decreases in the TMR head while maintaining high signal quality, thereby resolving the contradiction between improved signal-to-noise ratio and maintained resistance value stability
Solution Approach 2:
The patent uses a composite magnetic layer structure containing ferromagnetic hexagonal ferrite powder with specific crystallographic orientation characteristics. This composite material approach allows the magnetic layer to provide both high signal quality and resistance value stability, resolving the contradiction between signal-to-noise ratio and resistance value stability
3Productivity
If the data track width is narrowed to increase the number of data tracks, then the recording density is improved, but the head tracking accuracy deteriorates
Solution Approach 1:
The patent optimizes the XRD intensity ratio (Int(110)/Int(114)) to be within 0.5 to 4.0, which improves the magnetic layer's magnetic properties and signal characteristics. This enables better head tracking accuracy even with narrow data track width, thereby resolving the contradiction between increased recording density and maintained head tracking accuracy
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 significant resistance value decreases in the TMR head, maintaining high sensitivity and accuracy in head tracking servo, even with high smoothness of the magnetic tape surface, thereby enhancing the recording and reproducing capabilities of the magnetic tape device.
Implementation Method 1
a tunnel magnetoresistance effect type element as a servo pattern reading element
Implementation Method 2
a magnetic layer including ferromagnetic powder and a binding agent on the non-magnetic support, the magnetic layer includes a servo pattern, the ferromagnetic powder is ferromagnetic hexagonal ferrite powder
Data Source
AI summary
A magnetic tape device includes a TMR head as a servo head; and a magnetic tape which includes a magnetic layer including ferromagnetic hexagonal ferrite powder and a binding agent, and including a servo pattern. The XRD intensity ratio (Int(110)/Int(114)) of the hexagonal ferrite crystal structure obtained by an X-ray diffraction analysis of the magnetic layer using an In-Plane method is 0.5 to 4.0. The vertical direction squareness ratio of the magnetic tape is 0.65 to 1.00. The center line average surface roughness Ra measured regarding the surface of the magnetic layer is less than or equal to 2.0 nm, and the logarithmic decrement acquired by a pendulum viscoelasticity test performed regarding the surface of the magnetic layer is less than or equal to 0.050.