Magnetic Disk Head Controller Sampling Time Correction
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Solution Overview
Problem
Magnetic disk devices face challenges in accurately controlling magnetic heads during seek operations due to variations in sampling time caused by gaps between servo zones, leading to transient response issues and seek noise.
Innovation Solution
A magnetic disk device with a head controller that corrects model position and velocity by reflecting variations in sampling time when switching between zones, using a model that simulates magnetic head positions and velocities, and adjusts the write frequency of servo patterns across different zones to optimize data area utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If servo patterns are divided into multiple zones with different write frequencies to increase data area, then data area utilization is improved, but sampling time variation increases causing transient response issues and seek noise
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the model position and model velocity based on the current zone's write frequency. When switching between zones with different write frequencies, the controller corrects the sampling time variation by modifying these parameters, thereby maintaining seek control accuracy while allowing different write frequencies across zones to maximize data area utilization.
Solution Approach 2:
The patent implements feedback by continuously monitoring the current zone identification and using this information to adjust the model position and model velocity. The controller feeds back the zone switching information to correct sampling time variations, ensuring that seek control remains accurate despite the varying write frequencies across different zones.
2Area of stationary object
If write frequency of servo patterns is increased in outer circumference zones to increase data area, then data area is improved, but sampling time variation causes transient response and seek noise
Solution Approach 1:
The patent changes the model position and model velocity parameters according to the zone's write frequency characteristics. By detecting which zone the magnetic head is currently in and adjusting these parameters accordingly, the system compensates for sampling time variations that would otherwise cause seek noise, thereby enabling higher write frequencies in outer zones to maximize data area without generating harmful seek noise.
Data Source
AI summary
According to one embodiment, a magnetic disk device includes: magnetic heads; a magnetic disk in which servo patterns having different write frequencies from one another are divided and recorded into a plurality of zones; and a head controller configured such that, when performing seek control of the magnetic heads based on a model position and a model velocity obtained from a model which simulates the magnetic heads, the head controller corrects the model position and the model velocity, at the time of switching of the zones, so as to reflect variation of sampling time resulting from gaps between the zones.