Read/Write Head Feed Pitch Correction for Servo Pattern Accuracy
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Solution Overview
Problem
Existing methods for forming servo patterns on storage media face challenges such as accuracy issues and increased costs due to variations in feed speed, leading to incomplete or incorrectly written patterns, and fail to account for variations in writing and reading core widths of the read/write head.
Innovation Solution
An information storage apparatus and method that corrects the initial feed pitch of the read/write head using a pitch correction module, based on the first and second servo patterns, to accurately position the head for forming a third servo pattern with absolute position information, thereby ensuring precise recording and reproduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the feed speed in radius direction of the head is increased to reduce writing time, then productivity is improved, but manufacturing precision deteriorates due to wide track pitch and incomplete servo pattern writing
Solution Approach 1:
The patent applies preliminary action by first forming a spiral servo pattern at a moderate feed speed to establish a reference pattern, then using this pre-formed pattern to guide subsequent radial servo pattern writing. This preliminary spiral pattern serves as a foundation that enables accurate positioning for the final radial pattern, resolving the contradiction between writing speed and precision.
Solution Approach 2:
The patent replaces direct mechanical control of feed speed during radial servo writing with a computational approach. Instead of relying solely on mechanical precision to maintain track pitch at high speeds, the system uses signal processing to detect actual head positions from the spiral servo pattern and computationally determines corrected feed pitch values, substituting mechanical precision requirements with computational correction.
2Manufacturing precision
If the feed speed in radius direction of the head is decreased to improve track pitch accuracy, then manufacturing precision is improved, but productivity deteriorates due to extended writing time
Solution Approach 1:
The patent performs preliminary action by first writing the spiral servo pattern at a slower, more accurate feed speed to establish precise reference information. This initial slow writing phase creates a reliable foundation that enables subsequent faster radial pattern writing, as the corrected feed pitch values are derived from this pre-formed accurate reference.
Solution Approach 2:
The patent applies dynamics by making the feed pitch variable rather than constant. The system dynamically adjusts the feed pitch during radial servo pattern writing based on real-time detection of head position from the spiral servo pattern. This dynamic correction allows the system to operate at higher speeds while maintaining accuracy through continuous adaptation of the feed rate.
3Manufacturing precision
If an external servo track writer is used to write servo patterns on the entire surface of the storage medium, then manufacturing precision is improved, but device complexity increases and cost of investment increases
Solution Approach 1:
The patent extracts the servo pattern writing function from the external servo track writer and relocates it to the internal read/write head of the information storage apparatus. By taking out this function from the external facility, the system eliminates the need for complex external equipment while maintaining the ability to write accurate servo patterns using the corrected feed pitch methodology.
Solution Approach 2:
The patent applies universality by making the read/write head perform multiple functions: it serves both as the primary data read/write device and as the servo pattern writing device. This multi-functionality eliminates the need for separate external servo track writing equipment, reducing device complexity while maintaining manufacturing precision through the corrected feed pitch approach.
4Productivity
If the number of external servo track writers is increased to handle the entire surface writing task, then productivity is improved, but cost of investment increases
Solution Approach 1:
The patent makes the read/write head universal by enabling it to write servo patterns in addition to its primary data handling function. This single device performs what would otherwise require multiple specialized external servo track writers, maintaining writing capacity while eliminating the need for additional expensive equipment investments.
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
The solution enables high-precision positioning and recording of the read/write head, allowing for accurate formation of the third servo pattern, which enhances data recording and reproduction capabilities while reducing the likelihood of errors and costs associated with incomplete patterns.
Implementation Method 1
a method for magnetically writing the servo pattern within an information storage apparatus
Implementation Method 2
reading the second servo pattern with the read/write head
Data Source
AI summary
According to one embodiment, an information storage apparatus comprises a storage medium with a first servo pattern having absolute position information and a second servo pattern having relative position information, a pitch correction module configured to move a head with an initial feed pitch by using the second servo pattern by a target distance determined from the first servo pattern, and to correct the initial feed pitch based on a moving distance of the head and a target distance, a head position controller configured to position the head based on the initial feed pitch corrected by the pitch correction module and information of the first and the second servo patterns, and a recording signal generator configured to generate a control signal for making the head record the third servo pattern having the absolute position information.