Servo Signal Waveform Selection for Tape Tracking Accuracy
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Solution Overview
Problem
Magnetic head tracking in high-density magnetic tape recording systems is hindered by fluctuations in tape transport direction during servo signal writing, leading to inaccurate tracking and quality verification due to variations in pulsed signal current and tape tension.
Innovation Solution
A method and apparatus that select the portion of the servo signal waveform with less positional variation, specifically the trough portion corresponding to the rearward peak, for position regulation and quality verification, effectively mitigating the effects of tape transport direction fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the magnetic tape is transported with extremely high accuracy in position to accurately write a servo signal, then the servo signal writing accuracy is improved, but the system complexity and difficulty of achieving such high precision transport increases
Solution Approach 1:
The patent extracts and eliminates the harmful effects of transport direction fluctuations from the servo signal writing process. By using a fixed servo signal write head and allowing the magnetic tape to be transported at normal accuracy, the system separates the writing accuracy requirement from the transport precision requirement, thus reducing device complexity while maintaining servo signal writing accuracy.
Solution Approach 2:
The patent employs feedback mechanisms to monitor and compensate for transport direction fluctuations during servo signal writing. By detecting the actual position variations and adjusting the writing process accordingly, the system maintains high writing accuracy without requiring extremely precise transport control, thereby reducing overall system complexity.
2Manufacturing precision
If the magnetic tape is transported with extremely high accuracy in position to accurately write a servo signal, then the servo signal writing accuracy is improved, but the stability of the system under normal transport conditions deteriorates
Solution Approach 1:
The patent converts the harmful effect of transport direction fluctuations into a beneficial selection criterion. By deliberately allowing normal transport conditions with inherent fluctuations, the system identifies that the rearward peak position varies less than the forward peak position. This transforms the previously harmful fluctuation into a useful characteristic for selecting the more stable rearward peak for tracking control, thereby improving system reliability under normal transport conditions.
3Measurement precision
If the peak position is selected from the waveform for position regulation, then the magnetic head tracking accuracy is improved, but the sensitivity to transport direction fluctuations increases
Solution Approach 1:
The patent applies asymmetry by selecting the rearward peak position rather than the forward peak position for tracking control. The rearward peak inherently exhibits less variation in position under transport direction fluctuations. This asymmetric selection creates an inherent immunity to the harmful fluctuations, allowing high tracking accuracy to be achieved while reducing sensitivity to transport direction variations.
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 enhances the accuracy and stability of magnetic head tracking and servo signal quality verification by utilizing the less variable peak position for position control, thereby reducing the adverse effects of tape transport direction fluctuations.
Implementation Method 1
a magnetic head to follow a perpendicular recording-type magnetic tape... with a servo signal written therein
Implementation Method 2
a magnetic pattern composed of a first portion magnetized in one direction that is one of two opposite thickness directions and a second portion magnetized in a direction opposite to the one direction
Data Source
AI summary
A servo signal in which a magnetic pattern composed of a first portion magnetized in one direction that is one of two opposite thickness directions and a second portion magnetized in a direction opposite to the one direction is repeatedly arranged in a longitudinal direction of the tape at predetermined intervals is read out and a waveform of the servo signal is acquired from the readout servo signal. In the acquired waveform of the servo signal, a unit waveform having a pair of peaks of opposite polarities corresponding to the magnetic pattern appears periodically. A crest or trough portion of the waveform containing one of the peaks located rearwardly in the tape transport direction in a time of writing the servo signal is selected from the unit waveform contained in the acquired waveform of the servo signal. Tracking control or servo signal verification is performed based on the selected portion.