Optical Pickup Crosstalk Reduction via Beam Cross-Section Division
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Solution Overview
Problem
Existing optical medium reproduction technologies face challenges in reducing crosstalk and increasing linear-density density without complicating the optical pickup configuration, as they often require multiple beams and synchronization processes.
Innovation Solution
An optical medium reproduction device that uses a detection unit to form detection signals by dividing the beam into regions and a multi-input equalizer unit to process these signals, allowing for binarization and reduction of crosstalk using a single track reading output, thereby simplifying the optical pickup configuration and increasing density in both radial and linear directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If multiple beams are used to read tracks for crosstalk cancellation, then crosstalk reduction is achieved, but optical pickup configuration becomes complicated
Solution Approach 1:
The beam is divided into multiple regions (first region, second region, third region) in the cross-section, with each region corresponding to a different channel. This segmentation allows crosstalk cancellation by processing signals from different spatial regions separately and combining them with appropriate weighting, achieving crosstalk reduction without requiring multiple physical beams or complex optical paths
Solution Approach 2:
Instead of using multiple beams in the spatial domain, the invention divides the single beam's cross-section into multiple regions and processes them as separate channels. This transforms a spatial multiplicity problem into a cross-sectional region processing problem, simplifying the optical pickup while maintaining crosstalk cancellation capability
2Object-affected harmful factors
If three tracks are sequentially reproduced with a single beam for crosstalk cancellation, then crosstalk is reduced, but synchronization complexity and memory requirements increase
Solution Approach 1:
The detection unit performs preliminary separation of the beam cross-section into multiple regions, creating distinct channel signals before they enter the equalizer unit. This preliminary action allows the equalizer to process all channels simultaneously without requiring sequential reproduction and post-processing synchronization, eliminating the need for synchronization memory and complex timing control
3Quantity of substance
If channel bit length is reduced to increase linear density, then storage capacity increases, but inter-symbol interference increases
Solution Approach 1:
Different regions of the beam cross-section are assigned to different channels with specific weighting factors. The equalizer unit applies local processing to each channel's signal, optimizing the signal quality for that specific region. This local quality approach allows the system to handle reduced channel bit lengths by compensating for inter-symbol interference through region-specific equalization, maintaining signal reliability while enabling increased storage capacity
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 crosstalk and allows for a simpler optical pickup configuration, enabling increased density without the need for multiple beams or synchronization, thus enhancing data storage capacity.
Implementation Method 1
an optical filter configured to, when a beam returning from the optical medium is incident, form a plurality of signals having space-optically different bands in a linear-density direction and a track-density direction
Implementation Method 2
a detection unit configured to form detection signals of respective channels by dividing a cross-section of a beam returning from the optical medium into a plurality of regions and performing division into at least one channel corresponding to the region at an outer side in a radial direction, at least one channel corresponding to the region that is different in position in a tangential direction, and a channel corresponding to the other regions
Implementation Method 3
a multi-input equalizer unit configured to include a plurality of equalizer units to which the respective detection signals of the plurality of channels are supplied, and configured to form an equalized signal on the basis of the detection signals of the plurality of channels
Implementation Method 4
a binarization unit configured to perform a binarization process on the equalized signal to obtain binary data
Data Source
AI summary
An optical medium reproduction device includes: a detection unit configured to form detection signals of respective channels by dividing a cross-section of a beam returning from the optical medium into a plurality of regions and performing division into at least one channel corresponding to the region at an outer side in a radial direction, at least one channel corresponding to the region that is different in position in a tangential direction, and a channel corresponding to the other regions, and, in a case of forming the detection signals of the channels, form the detection signal of at least one of the channels by weighting and adding a signal in a predetermined region among the plurality of regions; a multi-input equalizer unit configured to include a plurality of equalizer units to which the respective detection signals of the plurality of channels are supplied, and configured to form an equalized signal on the basis of the detection signals of the plurality of channels; and a binarization unit configured to perform a binarization process on the equalized signal to obtain binary data.