Position Detecting Device Using Segmented Servo Information
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Solution Overview
Problem
In magnetic disk devices, achieving high recording density and accurate position detection is challenging due to errors in determining the actual position and velocity of the head during seek operations, which can lead to failure in reaching the target position.
Innovation Solution
A position detecting device that divides positional information into upper and lower digits, using a state observer to estimate and correct the position and velocity, and storing servo information in servo regions to enable accurate seek control, thereby improving storage density and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If recording density is increased to achieve higher storage capacity, then storage density is improved, but position detection accuracy deteriorates due to errors in determining head position and velocity during seek operations
Solution Approach 1:
The patent segments the determination of head position into two independent components: upper digit information (coarse position) obtained periodically from servo patterns, and lower digit information (fine position) obtained simultaneously. This segmentation allows each component to be optimized independently, with the upper digits providing periodic positional updates and the lower digits providing continuous fine positioning, thereby maintaining accuracy even at high recording densities where traditional continuous methods fail.
2Measurement precision
If continuous position monitoring is used to improve seek accuracy, then position control accuracy is improved, but the system complexity increases due to the need for continuous high-precision measurements
Solution Approach 1:
The patent implements periodic action by obtaining upper digit information at regular intervals from periodically arranged servo patterns on the disk, while lower digit information is obtained simultaneously and continuously. This periodic sampling of coarse position combined with continuous fine position measurement reduces the burden on the measurement system compared to fully continuous high-precision monitoring, while still achieving accurate seek control through the combined information.
Data Source
AI summary
According to one embodiment, a position detecting device includes a detecting portion which periodically detects a plurality of pieces of information generated in accordance with positional information divided into upper digits and lower digits. The upper digits are further divided into a plurality of pieces of upper digit information equal to the number of the period. The pieces of the upper digit information are obtained in a predetermined order. The lower digits are obtained simultaneously with any one of the pieces of the upper digit information. The positional information is divided so that the number of values, which are obtainable in one piece of the upper digit information provided by dividing the upper digits, and a division number of the upper digits are coprime.