Cache Buffer for DVD-ROM Defect Replacement Head Movement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The frequent back-and-forth movements of a pick-up head between the user data area and the spare area during sequential reading procedures increase the load and degrade the stability of reading apparatuses for information recording media, such as DVD-ROMs, due to the conventional method of replacing defects in spare areas.
Innovation Solution
A method and apparatus that utilize a cache buffer to store and manage replacements for defects, reducing the need for frequent head movements by pre-reading and buffering neighboring replacements during sequential reading, allowing the pick-up head to read data from the cache instead of repeatedly switching between the user data and spare areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If replacements for defects are stored in the spare area and read sequentially, then data integrity is maintained, but the pick-up head must frequently move back and forth between user data area and spare area
Solution Approach 1:
The patent applies preliminary action by pre-reading replacement data from the spare area and storing it in a buffer before the actual reading process. When a defect is detected, the corresponding replacement data is already available in the buffer, eliminating the need for frequent head movements to the spare area during sequential reading operations.
Solution Approach 2:
The patent introduces a buffer as an intermediary component between the spare area and the reading apparatus. This buffer temporarily stores replacement data, acting as a mediator that reduces direct interactions between the pick-up head and the spare area, thereby minimizing head movement frequency while maintaining data integrity.
2Ease of manufacture
If replacements are allocated from outermost to innermost in spare area, then allocation is simplified, but reading efficiency decreases due to frequent seeking operations
Solution Approach 1:
The patent performs preliminary allocation of replacement data to specific buffer locations based on their corresponding defect positions. By pre-organizing replacement data in the buffer according to sequential reading order, the system maintains simple allocation logic while enabling efficient sequential access without frequent seeking operations.
3Loss of information
If the pick-up head reads replacements from spare area during sequential reading, then complete data sequence is obtained, but reading apparatus load increases and stability degrades
Solution Approach 1:
The buffer serves as an intermediary that decouples the reading apparatus from frequent access to the spare area. By storing replacement data in the buffer, the system ensures data completeness is maintained while significantly reducing the mechanical load and stability degradation caused by frequent pick-up head movements.
Solution Approach 2:
The system performs preliminary loading of replacement data into the buffer before sequential reading operations begin. This preliminary action ensures that all necessary replacement data is readily available, maintaining data completeness while eliminating the need for the pick-up head to repeatedly access the spare area during reading, thus improving apparatus stability.
Data Source
AI summary
An information recording medium reading method is provided. The information recording medium has a user data area for recording data and at Least one spare area for recording replacements for defects of the user data area. The method includes steps of sequentially reading the user data area upon a registered defect is read. searching a corresponding replacement for the registered defect in a cache buffer; reading the corresponding replacement and neighboring replacements thereof from the spare area if the corresponding replacement is failed to be found in the searching step; storing the read replacements in the cache buffer; and repeating the above steps until a reading procedure is completed. A reading apparatus, which includes the cache buffer for storing the replacements and implements the above method, is also provided.