Disk Drive Defect Scanning Parallel Track Writing
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Solution Overview
Problem
Conventional defect scanning procedures in disk drives are time-consuming due to the need to sequentially write and read all tracks on the disk to identify defective areas, especially in drives with tens of thousands of tracks.
Innovation Solution
Implementing a defect scanning process that uses a wider write element to concurrently write test data across multiple tracks, reducing the time required for scanning by reading the data back one track at a time, thereby decreasing the overall test time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sequential writing and reading of all tracks is performed to identify defects, then measurement precision is improved, but loss of time worsens
Solution Approach 1:
The patent segments the track scanning process by dividing tracks into groups that can be scanned simultaneously. Instead of sequentially accessing each track, the method organizes tracks into multiple groups and scans multiple groups in parallel using multiple read/write heads, thereby reducing total test time while maintaining defect detection capability.
Solution Approach 2:
The patent merges multiple track scanning operations into a single parallel operation. By combining the scanning of multiple track groups into simultaneous operations using multiple heads, the system achieves faster defect detection without sacrificing measurement precision, directly addressing the time vs. accuracy contradiction.
2Reliability
If all tracks are scanned to ensure complete defect identification, then reliability is improved, but productivity worsens
Solution Approach 1:
The patent divides the complete track set into multiple segments or groups that can be processed simultaneously. This segmentation allows the system to maintain comprehensive defect identification (reliability) while increasing scanning throughput (productivity) by processing multiple segments in parallel rather than sequentially.
Solution Approach 2:
The patent transitions from one-dimensional sequential scanning to multi-dimensional parallel scanning by introducing multiple read/write heads operating simultaneously on different track groups. This dimensional change enables complete defect identification across all tracks while significantly improving scanning productivity through parallel processing.
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 approach significantly reduces the total test time by writing test data across multiple tracks simultaneously, resulting in a 25-38% decrease in the total test time compared to conventional methods, as shown in Table 1.
Implementation Method 1
A disk in a disk drive is coated with a magnetic material which is magnetized with a write element (e.g. write coil) in order to write data onto the surface of the disk
Data Source
AI summary
Apparatus and methods for performing defect scanning on a disk drive which includes a disk constructed to have tracks written on the disk for storing data. Test data is concurrently written in more than one track on the disk and the data written to the more than one track is read to detect defects on the disk.