Optical Filter Spatial Separation for Crosstalk Cancellation
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Solution Overview
Problem
Existing optical medium reproducing devices face challenges with inter-code interference and adjacent track crosstalk, particularly in high-density recording, where existing methods complicate the optical pickup configuration and increase circuit complexity, and do not effectively address defects or optimize performance in linear density densification.
Innovation Solution
An optical medium reproducing device that spatially and optically forms signals with different bands in the tangential and radial directions using an optical filter, and processes these signals with an electrical filter to reduce errors and improve signal quality by operating between regions, thereby reducing the influence of defects and inter-code interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If three beams are used to read the track to be reproduced and the tracks on both sides simultaneously, then crosstalk can be canceled, but the optical pickup configuration becomes intricate and phase synchronizing becomes complex
Solution Approach 1:
The patent divides the light receiving surface into multiple regions (first region and second region) to separately detect signals from different tracks. This segmentation allows crosstalk cancellation by comparing signals from adjacent tracks without requiring complex three-beam simultaneous reading, thereby simplifying the optical pickup configuration while maintaining reliability.
Solution Approach 2:
The patent transitions from temporal synchronization of multiple beams to spatial separation of signal detection by dividing the light receiving surface into different regions. This dimensional change from time-based to space-based processing simplifies the system architecture while achieving the same crosstalk cancellation effect.
2Reliability
If a memory is added for phase synchronizing, then crosstalk cancellation can be achieved, but the circuit scale increases
Solution Approach 1:
The patent extracts only the necessary signal components from different track regions and processes them directly through arithmetic operations. By taking out only the essential signal portions needed for crosstalk cancellation and eliminating the need for complete phase synchronizing memory systems, the circuit scale is reduced while maintaining reliability.
Solution Approach 2:
The patent replaces the mechanical/memory-based phase synchronizing system with direct arithmetic processing of spatially separated signals. This substitution eliminates the need for large memory circuits while achieving the same functional outcome through simpler computational operations.
3Quantity of substance
If densification is performed in the linear density direction by shortening mark length, then recording capacity increases, but inter-code interference increases
Solution Approach 1:
The patent applies different processing weights to different regions of the light receiving surface, with stronger weighting given to the center region and reduced weighting to edge regions. This local quality differentiation allows the system to maintain high recording capacity through densification while suppressing inter-code interference by emphasizing the stronger center signal over weaker edge signals.
Solution Approach 2:
The patent changes the signal processing parameters by applying adaptive weighting coefficients to different spatial regions. This parameter adjustment allows the system to optimize the balance between maintaining high recording capacity and suppressing inter-code interference caused by shortened mark lengths.
4Quantity of substance
If track pitch is narrowed to increase recording capacity, then densification is achieved, but adjacent track crosstalk increases
Solution Approach 1:
The patent segments the light receiving surface into multiple regions corresponding to different tracks, allowing separate detection and processing of signals from adjacent tracks. This segmentation enables the system to maintain narrow track pitch for high capacity while canceling crosstalk through regional signal comparison.
Solution Approach 2:
The patent converts the harmful crosstalk signal from adjacent tracks into a useful component by deliberately detecting it in separate regions and using it for cancellation processing. This approach transforms the harmful adjacent track interference into a beneficial element for improving signal accuracy.
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
The solution effectively reduces error rates when reproducing discs with defects, improving signal quality and simplifying the device configuration by operating on the difference between regions, thus enhancing the reproduction of high-density data.
Implementation Method 1
an optical filter configured to receive an incident returned light beam from the optical medium, and to spatially and optically form a plurality of signals having different bands in a tangential direction and a radial direction
Data Source
AI summary
There is provided an optical medium reproducing device configured to optically reproduce an optical medium including a plurality of tracks formed, the optical medium reproducing device including: an optical filter configured to receive an incident returned light beam from the optical medium, and to spatially and optically form a plurality of signals having different bands in a tangential direction and a radial direction; an arithmetic unit configured to operate the plurality of first signals formed by the optical filter so as to form a plurality of channels of second signals; and an electrical filter configured to individually receive the second signals, and to perform processing to the second signals so as to acquire a reproduced signal.