Optical Disc Address Coding to Block Incorrect Format Detection
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Solution Overview
Problem
Conventional optical disc reproduction systems face issues with obtaining incorrect addresses and malfunctions when reproducing discs with incompatible formats, particularly due to synchronization shifts and differences in error correction code formats, leading to incorrect address detection and data corruption.
Innovation Solution
The method involves performing bit inversion on specific symbols of error-correction-coded address information to generate conversion information, which is recorded on the optical disc, allowing for error detection without reproducing incorrect address information, even when the reproduction system is not compatible with the original format, by ensuring the number of symbol errors exceeds the correction capability of the Reed-Solomon code.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the correction capability of the error correction code is improved by adding more parity symbols, then the address detection accuracy is improved, but the code length increases and device complexity increases
Solution Approach 1:
The patent changes the parameter of error correction code format from RS(15,8,8) to RS(13,6,8), modifying the number of data symbols and parity symbols while maintaining the same code length. This parameter change improves correction capability (from correcting 3 symbol errors to 4 symbol errors) without increasing code length, thus resolving the contradiction between detection accuracy and device complexity
2Reliability
If a new format disc with improved error correction capability is reproduced by a conventional apparatus, then the code word can be reproduced, but incorrect address information is reproduced due to format incompatibility
Solution Approach 1:
The patent performs preliminary error detection before address reproduction by checking whether the reproduced address information matches the expected format and range. This preliminary action prevents incorrect address information from being used, resolving the contradiction between code word reproduction reliability and address information accuracy
Solution Approach 2:
The patent implements feedback mechanisms where the reproduced address information is verified against validation criteria (such as checking if the address falls within valid ranges or matches expected patterns). This feedback loop detects format incompatibility and prevents incorrect address reproduction, resolving the contradiction
3Measurement precision
If the optical spot is moved to a position close to an address by repeated operations, then the positioning accuracy is improved, but the time consumption increases
Solution Approach 1:
The patent performs preliminary positioning by first locating the general area of the address using the reproduced address information, then performs fine positioning only if needed. This preliminary action reduces the number of repeated movements required, resolving the contradiction between positioning accuracy and time consumption
Data Source
Figure 1A~2A
Figure 2B~3A
Figure 3B~4A
AI summary
According to the present invention, when an apparatus performs reproduction from an optical disc of a format not compatible to the apparatus, the apparatus is prevented from obtaining an incorrect address and thus causing a malfunction. A recording method according to the present invention performs first conversion of bit-inverting m number (1 ≤ m < n; m an integer) of symbols at prescribed positions of a code word coded using an error correction code by a Reed-Solomon code and including symbol C(i) [i = 0, 1, 2, ... n; n is an integer] to generate conversion information; and records the conversion information on a first recording medium. The first conversion is set such that a distance between first information obtained by performing inverse conversion to the first conversion on the conversion information, and second information obtained by performing inverse conversion to second conversion, which is different from the first conversion, on the conversion information, is at least 1/2 of a minimum free distance of the error correction code.