Optical Disc Run-In Bit Pattern for Stable PLL Locking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional optical disc recording formats face challenges in maintaining stable data reproduction and error correction when the spatial frequency of the shortest bit length exceeds the optical transfer function (OTF) cutoff frequency, leading to waveform distortion and inaccurate bit border detection, which hampers the locking capabilities of reproduction clock generation PLL circuits and adaptive equalization circuits.
Innovation Solution
The introduction of a run-in bit pattern in the optical disc that excludes bit patterns corresponding to frequencies higher than the OTF cutoff frequency, incorporating a combination of bit lengths with varying differences, and featuring longer run-in synchronization patterns to facilitate stable locking and error-free data reproduction, even when the spatial frequency of the shortest bit length surpasses the OTF cutoff frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the spatial frequency of the shortest bit length is increased to enhance recording density, then the recording capacity is improved, but the waveform distortion and inter-code interference increase due to exceeding the OTF cutoff frequency
Solution Approach 1:
The patent applies local quality by using different bit length combinations in different regions of the run-in area. Specifically, it employs bit patterns with longer bit lengths (lower spatial frequencies) in certain zones to ensure detectable waveforms, while allowing shorter bit lengths (higher spatial frequencies) in other zones to maximize recording density. This spatial variation in bit pattern characteristics resolves the contradiction between high recording density and waveform distortion.
Solution Approach 2:
The patent changes the parameter of bit length composition in the run-in area by excluding bit patterns with spatial frequencies higher than the OTF cutoff frequency. Instead, it uses bit patterns with spatial frequencies at or below the cutoff frequency, ensuring that the reproduction signal amplitude remains sufficiently high (100% or more) while still enabling high recording density through optimized bit length selection.
2Quantity of substance
If the shortest bit length is reduced to increase recording density, then the recording capacity is improved, but the detection precision of bit borders deteriorates due to amplitude reduction
Solution Approach 1:
The patent ensures bit border detection precision by locally optimizing the bit pattern composition in the run-in area. It excludes bit patterns with spatial frequencies exceeding the OTF cutoff frequency, which would cause amplitude reduction and detection failure. Instead, it uses bit patterns with spatial frequencies at or below the cutoff frequency, guaranteeing sufficient reproduction signal amplitude for accurate bit border detection while maintaining high recording capacity.
Solution Approach 2:
The patent uses the run-in area as a temporary zone with specialized bit patterns that are not optimized for maximum density but for reliable detection. This disposable run-in area with its carefully selected bit lengths enables the reproduction device to achieve stable locking and accurate synchronization before processing the high-density data area, effectively sacrificing the density optimization in this preliminary section to ensure overall system reliability.
3Quantity of substance
If conventional run-in bit patterns are used with high spatial frequency, then the recording density is maximized, but the locking capability of reproduction clock generation PLL circuits and adaptive equalization circuits deteriorates
Solution Approach 1:
The patent applies local quality by using different bit length combinations in different regions of the run-in area. Specifically, it employs bit patterns with longer bit lengths (lower spatial frequencies) in certain zones to ensure detectable waveforms and stable locking, while allowing shorter bit lengths (higher spatial frequencies) in other zones to maximize recording density. This spatial variation in bit pattern characteristics resolves the contradiction between high recording density and locking capability.
Solution Approach 2:
The patent changes the parameter of bit length composition in the run-in area by excluding bit patterns with spatial frequencies higher than the OTF cutoff frequency. Instead, it uses bit patterns with spatial frequencies at or below the cutoff frequency, ensuring that the reproduction signal amplitude remains sufficiently high (100% or more) while still enabling high recording density through optimized bit length selection.
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 solution enables stable locking and error-free data reproduction by ensuring the detection of run-in synchronization patterns, even when the spatial frequency of the shortest bit length exceeds the OTF cutoff frequency, thereby preventing continuous data errors and maintaining accurate bit border detection.
Implementation Method 1
an optical head 1001, a motor 1002, a servo circuit 1003
Data Source
AI summary
A bit pattern for a run-in area which allows data reproduction to be performed stably even when the recording density of an optical disc is increased is provided. An optical disc according to the present invention includes tracks, each of which divided into a plurality of recording blocks. Each of the plurality of blocks includes a run-in area and a data area. In the run-in area, a prescribed run-in bit pattern is recordable; and in the data area, bit patterns having a plurality of bit lengths obtained by modulating data as a recording target in accordance with a prescribed modulation rule are recordable. In this optical disc, at least one of spatial frequencies corresponding to the bit patterns having the plurality of bit lengths is higher than a cutoff frequency. The run-in bit pattern recordable in the run-in area includes the bit patterns having the plurality of bit lengths, from which the bit pattern corresponding to the frequency higher than the OTF cutoff frequency has been excluded.