TMR Servo Reader Shielding for Tape Head Shorting
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Solution Overview
Problem
Magnetic storage systems face challenges with TMR servo reader sensors due to susceptibility to scratching, leading to electrical shorts and reduced sensitivity, while GMR sensors have lower sensitivity and precision issues, limiting track density and precision in tape storage systems.
Innovation Solution
A servo reader transducer structure with a current-perpendicular-to-plane sensor between upper and lower shields, an electrical lead layer, and a spacer layer between the lead layer and the shields, enhancing protection against shorting and allowing for the use of TMR servo readers in writer modules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If TMR servo reader sensors are used to increase sensitivity and track resolution, then measurement precision is improved, but reliability deteriorates due to susceptibility to scratching and electrical shorting
Solution Approach 1:
The patent applies beforehand cushioning by depositing a sacrificial ductile metal layer (such as aluminum, titanium, or chromium) between the TMR servo reader sensor and the magnetic tape medium. This layer is intentionally placed to be scratched and smeared by abrasive particles before they can reach and damage the sensor, thereby cushioning the sensor from direct contact with harmful asperities on the tape surface
Solution Approach 2:
The patent introduces an intermediary ductile metal layer that acts as a mediator between the TMR sensor and the magnetic tape medium. This intermediate layer absorbs the mechanical stress and scratching from tape asperities, preventing direct contact between the harmful particles and the sensitive sensor elements, thus resolving the contradiction between high precision and reliability
2Reliability
If GMR servo readers are used to avoid scratching issues, then reliability is improved, but measurement precision deteriorates due to lower sensitivity and wider sensor requirements
Solution Approach 1:
The patent changes the physical parameters of the sensor structure by using a ductile metal sacrificial layer with specific material properties (ductility, conductivity) that differ from both the GMR and TMR sensor materials. This parameter change allows the system to achieve the reliability of GMR sensors while enabling the use of more sensitive TMR sensors, effectively resolving the trade-off between reliability and precision
3Measurement precision
If the sensor is placed in near contact with the tape to improve coupling, then measurement precision is improved, but object-affected harmful factors worsen due to increased susceptibility to scratching
Solution Approach 1:
The ductile metal sacrificial layer serves as an intermediary that allows the sensor to maintain near-contact positioning with the tape medium for optimal magnetic field coupling, while simultaneously protecting the sensor from direct scratching by abrasive particles on the tape surface. The intermediary layer absorbs the mechanical damage while preserving the magnetic coupling efficiency
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 reduces the likelihood of electrical shorting, enabling reliable bi-directional tape operation and maintaining sensor sensitivity, allowing for closer spacing to the media and improved track following and density in magnetic storage systems.
Implementation Method 1
Tunneling magnetoresistive (TMR) servo readers are susceptible to scratching caused by contact with asperities fixed on moving magnetic medium surfaces
Implementation Method 2
The magnetic recording transducer then generates a magnetic field, which encodes the data into the magnetic media
Implementation Method 3
Data is read from the media by similarly positioning the magnetic read transducer and then sensing the magnetic field of the magnetic media
Data Source
AI summary
An apparatus according to one approach includes a servo reader transducer structure on a module. The servo reader transducer structure has a lower shield, an upper shield above the lower shield, the upper and lower shields providing magnetic shielding, a current-perpendicular-to-plane sensor between the upper and lower shields, an electrical lead layer between the sensor and one of the shields, and a spacer layer between the electrical lead layer and the one of the shields. The electrical lead layer is in electrical communication with the sensor. The conductivity of the electrical lead layer is higher than the conductivity of the spacer layer. An array of writers is also present on the module. Writer modules having this structure are less susceptible to shorting, and therefore enable use of TMR servo readers on writer modules.