Servo Write Method Using Spiral Time Interval Measurement
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Solution Overview
Problem
Magnetic disk devices face challenges in efficiently writing and reading spiral servo patterns due to variations in spiral time intervals and velocities across different areas of the disk, affecting data recording and retrieval precision.
Innovation Solution
A servo write method that measures and utilizes spiral time intervals to generate tables for writing servo patterns, allowing the head to move in opposite directions to adjust velocity and position, ensuring accurate and efficient data writing and reading across the disk's acceleration and constant velocity areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If spiral servo patterns are written radially from inner circumference to outer circumference, then data recording capacity is improved, but variations in spiral time intervals and velocities cause positioning precision to deteriorate
Solution Approach 1:
The patent performs preliminary measurement of spiral time intervals during the servo pattern writing process. The controller measures the actual time intervals at which spiral servo patterns are written across different radial positions, then uses these measured values to calculate correction amounts that compensate for velocity variations, ensuring accurate positioning in subsequent operations.
Solution Approach 2:
The patent implements a feedback mechanism where the measured spiral time intervals are used to generate correction amounts that are applied to adjust the head positioning. The controller continuously refines positioning accuracy by comparing measured time intervals against expected values and applying corrective adjustments to compensate for velocity variations across the disk surface.
2Productivity
If the head moves at varying velocities across acceleration and constant velocity areas, then writing efficiency is improved, but data retrieval precision deteriorates
Solution Approach 1:
The patent dynamically adjusts the head positioning based on the measured spiral time intervals that reflect the actual velocity variations during writing. The system adapts to changing writing conditions by calculating correction amounts that account for acceleration and constant velocity areas, allowing efficient writing while maintaining retrieval precision through real-time compensation.
Solution Approach 2:
The patent changes the positioning parameters by applying correction amounts derived from measured spiral time intervals. These parameter adjustments compensate for velocity variations across different radial positions and writing phases, ensuring that data retrieval precision is maintained even when writing efficiency is optimized through variable velocity operation.
3Device complexity
If servo patterns are written based on constant velocity assumptions, then device complexity is reduced, but positioning accuracy deteriorates
Solution Approach 1:
The system performs self-calibration by automatically measuring its own spiral time intervals during the servo writing process. The controller uses these self-measured values to generate correction amounts that improve positioning accuracy without requiring external calibration equipment or complex pre-programmed velocity profiles, maintaining simplicity while enhancing precision.
Solution Approach 2:
The patent performs preliminary measurement of spiral time intervals during the initial servo pattern writing phase. These measured values are stored and used to generate correction amounts that improve positioning accuracy in subsequent operations, avoiding the need for complex real-time velocity measurement systems while maintaining high precision.
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 method enhances data recording capacity and format efficiency by accurately positioning the head and writing servo patterns based on calculated spiral velocities and positions, improving data retrieval precision and disk performance.
Implementation Method 1
measuring a plurality of time intervals at which each of the spiral servo patterns is read in the first area
Data Source
AI summary
According one embodiment, a servo write method includes a head and a disk having a plurality of spiral servo patterns which are written radially in a first direction from a first area to a second area other than the first area at velocity that varies between the first area and the second area, the method including moving the head in a second direction opposite to the first direction to read each of the spiral servo patterns, measuring a plurality of time intervals at which each of the spiral servo patterns is read in the first area, and writing a plurality of servo patterns to the first area based on the time intervals.