Optical Disk Write Strategy Control for Jitter Reduction
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Solution Overview
Problem
Existing write strategies for optical disks face challenges in maintaining recording quality, particularly at high speeds and in multilayer disks, due to variations in equipment and disk performance, leading to issues like jitter and error rates, and require extensive testing and storage of multiple strategies to optimize laser power and pulse timing.
Innovation Solution
A semiconductor device that adjusts write strategies by processing error information related to phase shifts in reproduction signals, optimizing both overall and individual recording marks to minimize error and jitter, using a combination of coarse and fine adjustments to determine optimal laser pulse waveforms and power settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single recording pulse is used to form a recording mark, then the recording process is simple and fast, but thermal accumulation occurs causing non-uniform temperature distribution and tear-shaped recording marks
Solution Approach 1:
The patent applies periodic action by using a pulse train consisting of multiple short pulses instead of a single continuous pulse. The pulse train includes a first pulse, second pulse, third pulse, and fourth pulse with specific time intervals between them. This periodic pulsing allows thermal accumulation to be controlled, preventing excessive heat buildup while maintaining recording efficiency and producing uniform recording marks without tear-shaped distortions.
2Manufacturing precision
If a multipulse write strategy is used to reduce thermal accumulation, then recording mark shape uniformity improves, but at high-speed recording the pulse amplitude changes due to overshoot and undershoot causing inaccurate heat control
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the amplitude and time width parameters of each pulse in the pulse train based on recording speed conditions. At high-speed recording, the control mechanism modifies pulse parameters to compensate for overshoot and undershoot effects, ensuring accurate heat control. The system changes operational parameters adaptively to maintain recording mark quality across different recording speeds.
Solution Approach 2:
The patent implements feedback control mechanisms that monitor the actual recording conditions and adjust pulse parameters accordingly. The system detects overshoot and undershoot phenomena and uses feedback to correct pulse amplitude and timing, ensuring accurate heat delivery to the recording medium. This closed-loop control maintains reliable heat control even at high recording speeds where transient effects are more pronounced.
3Ease of manufacture
If predetermined write strategies are used for recording, then recording process is standardized, but variations in equipment and disk performance cause inappropriate mark length and edge position leading to degraded reproduction quality
Solution Approach 1:
The patent applies dynamics by transitioning from static, predetermined write strategies to dynamic, adaptive write strategies. The system continuously adjusts pulse parameters such as amplitude, time width, and timing positions based on real-time detection of actual recording conditions including mark length measurements. This dynamic adaptation allows the recording system to maintain optimal performance across variations in equipment and disk characteristics, producing accurate mark lengths and edge positions despite manufacturing tolerances and performance variations.
Solution Approach 2:
The patent implements self-service through automatic measurement and adjustment mechanisms that enable the recording system to self-optimize without external intervention. The system automatically measures actual mark lengths, detects deviations from target specifications, and adjusts subsequent pulse parameters accordingly. This self-adjusting capability allows the system to compensate for equipment and disk variations autonomously, maintaining high recording precision across different media and device conditions.
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 approach enables the efficient generation of high-quality write strategies that improve recording accuracy and reduce jitter across all recording marks, even at high speeds and in multilayer disks, by dynamically adjusting pulse parameters and laser power, thereby enhancing overall recording quality.
Implementation Method 1
laser light is applied onto a recording surface of the disk, so that a thermal change occurs in an optical storage medium to record information therein
Implementation Method 2
a recording pulse including a top pulse for preheating the recording surface of the optical disk
Data Source
AI summary
A semiconductor device mounted in an optical disk apparatus controls writing and reading of data in and from an optical disk. The device performs first processing for adjusting a write strategy in such a manner that based on error information corresponding to a shift in the phase of a reproduction signal with respect to a channel clock signal for data reproduction, which is generated based on the reproduction signal read from the optical disk, the value of the error information related to a plurality of recording marks to be evaluated becomes minimum as a whole. The device also performs second processing for adjusting a write strategy in such a manner that the value of the error information related to a desired recording mark becomes small.