Optical Recording Pulse Sequences for Multi-Layer Phase-Change Media
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Solution Overview
Problem
Multi-layered phase-change optical storage media suffer from unacceptable recording and overwrite characteristics due to inadequate thermal management and laser beam absorption in highly transparent data layers, which affects the ability to record and erase data effectively.
Innovation Solution
The use of specific recording pulse sequences, including a first recording pulse sequence for the most remote data layer and a second sequence for other data layers, with varying power levels and pulse structures to optimize temperature rise and control for each layer, ensuring efficient data recording and erasure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional single recording pulse sequence is used for all data layers, then the structure is simple, but recording and overwrite characteristics are unacceptable due to inadequate thermal management
Solution Approach 1:
The patent divides the recording pulse sequence into different types (first recording pulse sequence for the most remote data layer, second recording pulse sequence for other data layers) to address the thermal management needs of different layers. This segmentation allows each layer to receive optimized thermal treatment, resolving the contradiction between reliability and complexity.
Solution Approach 2:
The patent applies different recording pulse sequences to different data layers based on their specific thermal characteristics. The most remote data layer receives a different pulse sequence than closer layers, ensuring each layer gets locally optimized thermal management for reliable recording and overwriting.
2Speed
If the laser beam power is increased to achieve steep temperature rise in the recording film, then the temperature rise speed improves, but the temperature may exceed the melting point causing damage
Solution Approach 1:
The patent uses periodic pulsed laser irradiation with specific duty cycles and pulse widths to achieve rapid temperature rises followed by controlled cooling. This periodic action allows the recording film to reach necessary temperatures for phase change without exceeding the melting point, maintaining integrity while achieving fast temperature transitions.
Solution Approach 2:
The patent dynamically adjusts laser beam parameters (power, pulse width, duty cycle) based on the data layer being written to and the desired recording characteristics. This dynamic control enables steep temperature rises when needed while preventing overheating and damage to the recording film.
3Quantity of substance
If multi-layered structure is used to increase storage capacity, then the storage density improves, but thermal management becomes inadequate affecting recording effectiveness
Solution Approach 1:
The patent segments the multi-layered storage medium into different data layers with distinct thermal characteristics, applying specific recording pulse sequences to each layer. This segmentation enables independent thermal management for each layer, maintaining effectiveness despite the increased storage capacity provided by the multi-layered structure.
Solution Approach 2:
The patent changes recording parameters (laser power, pulse width, duty cycle) based on which data layer is being accessed and its thermal properties. This parameter adaptation ensures effective thermal management across multiple layers, allowing the system to maintain reliable recording performance while achieving high storage density through the multi-layered configuration.
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 enhances recording and overwrite characteristics by achieving steep temperature rises in the recording film, maintaining temperatures within the crystallization and melting points, thereby improving data integrity and storage efficiency in multi-layered phase-change optical storage media.
Implementation Method 1
a laser beam having a constant power (erasing power) lower than the recording power is emitted onto the recording film. The laser beam raises the temperature thereof to the crystallization temperature or higher but lower than the melting point
Implementation Method 2
to change the recording film from the amorphous phase to the crystalline phase to erase the recorded marks
Implementation Method 3
recording pulses are applied (emitted) onto a recording film with a laser beam having a specific power, to melt and rapidly cool down the recording film, thus forming amorphous recorded marks thereon
Implementation Method 4
to melt and rapidly cool down the recording film, thus forming amorphous recorded marks thereon
Data Source
AI summary
Data is recorded in a phase-change optical storage medium having data layers. A first recording pulse sequence is generated for recording to a first data layer located most remote from a beam-incident surface. The first sequence has a recording pulse carrying an erasing power and a recording power rising from the erasing power, and a cooling pulse carrying a bottom power lower than the erasing power. A second recording pulse sequence is generated for recording to a second data layer. The second sequence has recording pulse carrying an erasing power and a recording power rising from the erasing power, a cooling puse carrying a bottom power lower than the erasing power, and an erasing top pulse carrying an erasing top power higher than the erasing power.