Position Demodulation Apparatus Correcting Lissajous Distortions
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Solution Overview
Problem
Conventional hard disk drive systems face inaccuracies in positioning the magnetic head due to distortions in the Lissajous figure formed by position signals from servo patterns, which affects the precision of head positioning correction.
Innovation Solution
A position demodulation apparatus comprising a demodulation unit, an acquiring unit, a detecting unit, and a rotational correction unit that demodulates signals from servo patterns, acquires vector lengths and phase angles, detects the greatest phase angle, calculates correction amounts, and applies rotational correction to align vectors, thereby improving positioning accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional position signal correction methods are used, then positioning accuracy is improved, but the correction determination process is complex and time-consuming
Solution Approach 1:
The patent transforms the complex correction determination process into a parameter estimation problem by changing the approach from iterative correction analysis to direct parameter calculation. The rotational correction angle and amplitude correction ratio are calculated as closed-form parameters based on the Lissajous figure characteristics, eliminating the need for complex iterative procedures while maintaining positioning accuracy.
Solution Approach 2:
The patent replaces the mechanical iterative correction process with a mathematical parameter estimation system. Instead of using iterative algorithms to determine correction values, the system directly calculates correction parameters from the Lissajous figure geometry, substituting computational complexity with analytical mathematics.
2Measurement precision
If iterative correction analysis is performed to determine correction values, then positioning precision is improved, but processing time increases
Solution Approach 1:
The patent performs preliminary analysis of the Lissajous figure characteristics to directly determine correction parameters before the actual positioning operation. By pre-calculating the rotational correction angle and amplitude correction ratio from the Lissajous figure geometry, the system eliminates the need for time-consuming iterative corrections during data processing.
Solution Approach 2:
The patent changes the approach from time-consuming iterative correction analysis to direct parameter calculation. The correction values are computed as closed-form parameters based on Lissajous figure measurements, transforming a time-intensive process into a rapid parameter estimation that maintains positioning precision.
Data Source
AI summary
According to one embodiment, a position demodulation apparatus is provided which demodulates a first demodulated signal and a second demodulated signal, based on a servo-pattern read signal read out by a head from a medium, acquires a plurality of sets of a vector length and phase angle of vectors on a phase plane denoting the first and second demodulated signals, detects a phase angle for which the vector length is greatest based on the sets acquired, and executes rotational correction using the difference between the detected phase angle and a particular reference angle as a correction amount.