Optical Disc Error Detection Using Euclidean Distance Normalization
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Solution Overview
Problem
High-density recording on optical discs faces challenges with inter-code interference and Signal Noise Ratio (SNR) deterioration, particularly when recording density exceeds optical resolution, leading to errors in decoding due to thermal interference and noise influence.
Innovation Solution
An information reading and recording method that detects length and phase errors by analyzing differences in Euclidean distances between error patterns and a correct pattern, adjusting recording parameters to minimize errors and stabilize the recording process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If recording density is increased to achieve higher capacity, then productivity is improved, but manufacturing precision deteriorates due to inter-code interference and SNR deterioration
Solution Approach 1:
The patent employs feedback mechanisms by detecting reproduction signals from recorded marks and spaces, calculating Euclidean distances between actual signals and reference patterns, and using this information to adjust recording parameters. This closed-loop feedback system enables real-time optimization of recording conditions to maintain precision at high densities
Solution Approach 2:
The patent dynamically changes recording parameters including laser power levels, pulse widths, and recording speed based on detected signal quality and calculated errors. By adjusting these parameters in response to measured performance, the system optimizes the balance between recording capacity and mark precision
2Productivity
If recording marks and spaces are shortened to increase density, then productivity is improved, but measurement precision deteriorates due to decreased signal amplitude and increased thermal interference
Solution Approach 1:
The system uses feedback from reproduction signals to detect edge positions of recording marks and calculate length errors. By continuously monitoring the actual recorded patterns and comparing them with expected patterns, the system can precisely measure edge positions even when marks are very short
Solution Approach 2:
The patent applies asymmetric pulse waveforms where the leading edge and trailing edge of recording pulses have different characteristics. This asymmetric shaping helps distinguish mark edges from thermal interference and enables more accurate edge detection in high-density conditions where symmetry would cause ambiguity
3Manufacturing precision
If pulse waveform is fine-tuned for each space length to compensate thermal interference, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent implements dynamic adjustment of recording parameters based on real-time detection of space lengths and thermal interference levels. Rather than static pre-programmed settings, the system continuously adapts pulse waveforms and power levels according to the specific recording conditions, enabling precision without requiring complex manual configuration
Solution Approach 2:
The system automatically changes multiple recording parameters including peak power, bottom power, cooling power, and pulse widths based on detected space lengths and thermal interference. This coordinated parameter adjustment simplifies the user interface while maintaining high precision through complex internal optimizations
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 method effectively reduces error rates and enhances the stability of high-density recording by accurately adjusting recording conditions, even when recording density approaches or exceeds optical resolution limits.
Implementation Method 1
A recording power Pw of the multi-pulse train includes a peak power Pp201 having a heating effect, which is required to form recording marks
Implementation Method 2
a bottom power Pb202 and a cooling power Pc203 both having a cooling effect
Data Source
AI summary
According to the present invention, a first error pattern caused by a shift of a bit relating to a recording mark or a space of a shortest length and a second error pattern caused by an edge shift of the recording mark are used. For each of a plurality of error patterns, a pattern shift obtained by normalizing a difference between a square of a Euclidean distance between the error pattern and a reproduction signal and a square of a Euclidean distance between a correct pattern and the reproduction signal, using a square of a Euclidean distance between the correct pattern and the error pattern is detected. Length and phase errors are calculated by a sum of, or a difference between, a first pattern shift amount obtained by normalization performed using the first error pattern and a second pattern shift amount obtained by normalization performed using the second error pattern.