Position Error Signal Generation Using Inter-Track Interference Detection
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Solution Overview
Problem
As magnetic data storage densities increase, inter-track interference becomes a significant challenge for maintaining the read head's position accuracy on a single track, leading to signal distortion and reduced reliability in hard disk drives.
Innovation Solution
Implementing multiple read sensors on a single head assembly to detect and cancel inter-track interference, allowing for the generation of position error signals that adjust the head's position using a servo control loop, potentially eliminating or reducing the need for servo wedges and enhancing data storage density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If magnetic data storage density is increased, then storage capacity is improved, but inter-track interference increases causing position accuracy to deteriorate
Solution Approach 1:
The patent divides the read head into multiple independent read sensors (first read sensor, second read sensor, etc.) that can independently detect signals from different tracks. This segmentation allows the system to measure inter-track interference from adjacent tracks separately and cancel it out, thereby maintaining position accuracy even when storage density increases and track pitch decreases.
Solution Approach 2:
The patent uses data tracks as an intermediary to generate position error signals. By detecting inter-track interference from adjacent data tracks and using it to generate position error signals, the system can correct head positioning without requiring traditional servo wedges, thus maintaining accuracy at higher storage densities.
2Measurement precision
If traditional servo wedges are used for position feedback, then position control is achieved, but storage density is reduced due to space occupied by servo sectors
Solution Approach 1:
The patent makes data tracks serve multiple functions: they both store user data and provide servo information for position feedback. By detecting inter-track interference from adjacent data tracks, the system generates position error signals without needing separate servo wedges, thus eliminating the trade-off between servo space and data storage capacity.
Solution Approach 2:
The patent enables data tracks to self-generate position error signals through their own magnetic patterns. The inter-track interference from data tracks on adjacent tracks contains position information that can be extracted and used for head positioning, allowing the data tracks themselves to provide servo functionality without external assistance.
3Quantity of substance
If track pitch is decreased to increase storage density, then storage capacity is improved, but inter-track interference increases making position control more difficult
Solution Approach 1:
The patent converts the harmful inter-track interference into a useful signal source. By detecting the interference patterns from adjacent tracks and processing them through position error signal generation, the system transforms what was previously a detrimental effect into a valuable position feedback mechanism that improves head positioning 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
This approach effectively reduces inter-track interference, improving the accuracy of track following and allowing for increased data storage density by accurately positioning the read head, even with decreased track pitch, and can eliminate or reduce the frequency of servo wedges.
Implementation Method 1
a first read signal from a first read sensor positioned over a magnetic medium
Implementation Method 2
The preamplifier 26 generates a write current that flows through the write head of the head 20 when writing data. The write current is used to produce a magnetic field on the magnetic surfaces of the platters 16.
Implementation Method 3
Magnetic surfaces of the platters 16 induce low-level analog signals in the read head of the head 20 during reading of the platters 16.
Data Source
AI summary
A system including an inter-track interference detection module and a position error signal generation module. The inter-track interference detection module determines a first inter-track interference value based on a first signal from a first sensor positioned over a first track of a rotating storage medium. The first inter-track interference value indicates energy contributed by tracks adjacent to the first track compared to energy contributed by the first track. The inter-track interference detection module determines a second inter-track interference value based on a second signal from a second sensor positioned over a second track of the rotating storage medium. The second inter-track interference value indicates energy contributed by tracks adjacent to the second track compared to energy contributed by the second track. The position error signal generation module generates a position error signal based on the first inter-track interference value and the second inter-track interference value.