TMR Head Servo Tracking via Magnetic Tape Surface Engineering
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Solution Overview
Problem
In magnetic tape devices, the use of TMR heads as servo heads leads to a significant decrease in resistance value, affecting the accuracy of head tracking servo due to the sliding contact with the magnetic tape, which results in reduced signal-to-noise ratio (SNR) and increased errors in data track following.
Innovation Solution
A magnetic tape device with a TMR head using a magnetic tape having a non-magnetic support, a magnetic layer with ferromagnetic powder and a binding agent, and specific surface roughness and magnetic cluster area ratios to prevent resistance value decrease, ensuring high SNR and accurate head tracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a TMR head is used as a servo head in a magnetic tape device, then the sensitivity and signal-to-noise ratio are improved, but the resistance value decreases significantly due to sliding contact with the magnetic tape
Solution Approach 1:
A transfer layer is introduced between the TMR head and the magnetic layer to prevent direct sliding contact. This transfer layer acts as an intermediary that reduces wear and prevents resistance value decrease in the TMR head while maintaining high sensitivity and signal-to-noise ratio for servo pattern reading
Solution Approach 2:
The magnetic layer is designed with specific surface roughness parameters (Ra ≤ 2.0 nm) and magnetic cluster area ratios (0.80 ≤ Sdc/Sac ≤ 1.30) beforehand to cushion and distribute the sliding contact pressure, preventing excessive stress concentration that would cause TMR head resistance degradation
2Quantity of substance
If the recording density is increased to achieve high capacity, then the recording capacity is improved, but the magnetic signal becomes weaker
Solution Approach 1:
The magnetic layer parameters are optimized with specific surface roughness (Ra ≤ 2.0 nm) and magnetic cluster area ratios (0.80 ≤ Sdc/Sac ≤ 1.30) to enhance magnetic signal strength while maintaining high recording density, allowing both high capacity and weak signal readability
Solution Approach 2:
A composite structure is formed with ferromagnetic powder particles distributed in a binding agent matrix, creating magnetic clusters with optimized magnetic properties that maintain strong signals even at high recording densities
3Manufacturing precision
If the width of data track is narrowed to increase recording density, then the recording density is improved, but the head tracking accuracy deteriorates
Solution Approach 1:
Different regions of the magnetic tape are designed with different properties: servo patterns have specific magnetic characteristics for accurate head positioning, while data tracks have narrow widths for high density. The magnetic layer parameters (Ra ≤ 2.0 nm, 0.80 ≤ Sdc/Sac ≤ 1.30) ensure both servo reading accuracy and data track precision
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 SNR reading of servo patterns and prevents significant resistance value decreases in TMR heads, enhancing the accuracy of head tracking servo and maintaining the integrity of data tracks on the magnetic tape.
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
information is recorded on a magnetic recording medium as a magnetized pattern. Information recorded on a magnetic recording medium is reproduced by reading a magnetic signal obtained from the magnetized pattern by a magnetic head
Data Source
AI summary
The magnetic tape device includes a magnetic tape; and a servo head, in which the servo head is a TMR head, the magnetic tape includes a servo pattern in the magnetic layer, a center line average surface roughness Ra measured regarding a surface of the magnetic layer is equal to or smaller than 2.0 nm, a 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 a 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 thereof in an AC demagnetization state measured with a magnetic force microscope is 0.80 to 1.30.