Optical Disc Sync Pattern Detection Using Unequal Wobble Intervals

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Solution Overview

Problem

Conventional optical information recording systems face challenges in reliably detecting sync patterns in low SNR environments due to signal leakage and varying land track widths, which degrades the reproduction signal quality.

Innovation Solution

An optical information recording medium and device that employs a continuously wobbling groove with modulated address information, using a combination of first and second wobble patterns with unequal intervals for the sync pattern, allowing for accurate detection and decoding of address data even in poor SNR conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If data are recorded on both land and groove in a land/groove recording system, then recording capacity is increased, but SNR is degraded due to RF signal leakage from adjacent tracks

Engineering Contradiction:

Improverecording capacityVSAvoidSNR

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The sync pattern is segmented into multiple first wobble patterns with different intervals, allowing the detection system to identify the sync pattern through multiple reference points rather than relying on a single pattern, thereby improving detection reliability in low SNR conditions

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The first wobble patterns are arranged at unequal intervals, creating an asymmetric pattern that is easily distinguishable from regular data wobble patterns. This asymmetry provides a unique fingerprint for sync pattern detection, enabling reliable identification even when the overall SNR is degraded

Inventive Principle:

Principle #4Asymmetry

2Measurement precision

If address information is recorded by modulating the wobble in a continuously wobbling groove, then accurate address reproduction is enabled, but sync pattern detection becomes difficult in low SNR environments

Engineering Contradiction:

Improveaddress reproduction accuracyVSAvoidsync pattern detection difficulty

Core Design Contradiction:

Measurement precisionVSDifficulty of detecting and measuring

Solution Approach 1:

The sync pattern with its distinctive unequal interval structure is recorded beforehand in the address information area. This preliminary structured pattern serves as a reference that the detection system can use to establish synchronization before reading the actual address data, enabling accurate detection even in low SNR conditions

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The wobble pattern parameters are changed to create the sync pattern - specifically, the intervals between consecutive wobble patterns are varied (unequal intervals) rather than being uniform. This parameter change creates a detectable signature that distinguishes the sync pattern from regular data patterns, facilitating reliable detection

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS9966098B2Optical information recording medium and optical information recording medium reproducing device

Publication Date: 2018.05.08 SONY GROUP CORP

AI summary

Provided is an optical information recording medium including: a continuously wobbling groove formed in advance by a CAV or a zone CAV. Information is allowed to be recorded on the groove and a land adjacent to the groove, address information is recorded by modulating the wobble, the address information includes a sync pattern indicating a position of the address information and address data, and the sync pattern includes a plurality of first wobble patterns and a second wobble pattern between the first wobble patterns, and at least part of intervals of the first wobble patterns are set to unequal intervals.