Optical Recording Mark Shape Deviation Compensation
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Solution Overview
Problem
High-density optical recording technologies face challenges in achieving sufficient recording compensation performance due to thermal and intersymbol interference, which limits playback signal quality, especially at high recording densities where edge shifts and mark shape deviations become significant.
Innovation Solution
A method for recording state evaluation and compensation that calculates the deviation of a recording mark's shape from an ideal shape based on amplitude errors, using a level estimation vector to adjust the recording signal's level and edge positions, thereby reducing interference and improving playback performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-density recording is performed to increase storage capacity, then recording density is improved, but thermal interference and intersymbol interference increase causing playback signal quality to deteriorate
Solution Approach 1:
The patent changes the parameter of recording pulse shape by introducing a pre-emphasis component that boosts low-frequency components. This parameter modification allows the system to compensate for the degradation caused by high-density recording, maintaining playback signal quality while achieving high recording density.
Solution Approach 2:
The patent employs feedback by calculating the actual playback signal from recorded marks and comparing it with the original recording signal. Based on this comparison, the system adjusts and optimizes the recording pulse shape to minimize interference effects, creating a closed-loop control system that maintains signal quality at high densities.
2Quantity of substance
If recording mark length is shortened to increase density, then recording capacity is improved, but edge position deviation increases causing playback errors
Solution Approach 1:
The patent modifies the recording pulse parameters by adding a pre-emphasis component with specific time constants (Tp1, Tp2) that boost low-frequency components. This parameter change compensates for the edge position deviation that occurs when recording marks are shortened, maintaining manufacturing precision while increasing recording capacity.
3Quantity of substance
If space length between recording marks is reduced to increase linear density, then recording density is improved, but thermal interference increases affecting mark formation
Solution Approach 1:
The patent changes the recording pulse shape parameters by incorporating a pre-emphasis component that modifies the temporal distribution of energy. This parameter modification helps control the thermal profile during mark formation, reducing thermal interference effects even when the space length between marks is reduced to increase linear density.
4Ease of operation
If conventional edge shift-based recording compensation is used, then implementation simplicity is maintained, but compensation accuracy is insufficient for high-density recording
Solution Approach 1:
The patent changes the approach from simple edge shift adjustment to modifying the recording pulse shape parameters themselves. By adjusting the pre-emphasis time constants and gain in the pulse shape, the system achieves higher compensation accuracy while maintaining relatively simple implementation through parameter optimization rather than complex structural changes.
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 compensation performance and playback quality by accurately estimating and correcting mark shape deviations, achieving superior results compared to traditional edge shift-based methods, especially in high-density and multi-value recording scenarios.
Implementation Method 1
the recording layer of the recording medium is irradiated with recording laser light (appropriately referred to as "recording pulse") having a predetermined pulse shape whose intensity is modulated based on information to be recorded, and a physical state of the recording layer is changed to form a recording mark
Implementation Method 2
a playback signal is obtained by irradiating a recording mark and a space formed in a recording layer with playback laser light having low output power and detecting a change in optical characteristics of the recording mark and the space, for example, a change in reflectance
Data Source
AI summary
A recording mark is formed on a recording medium by a predetermined recording signal, a playback signal of the recording mark formed on the recording medium is obtained, and an expected value signal of the playback signal based on the recording signal is generated. Based on an amplitude error between the playback signal and the expected value signal, and for each predetermined unit of the recording signal, a deviation amount of a mark shape of the recording mark from which the playback signal is obtained with respect to a mark shape of an ideal recording mark is calculated, and a mark shape of the recording mark formed on the recording medium is estimated. Based on the deviation amount of the mark shape of the recording mark, a correction amount is calculated for each predetermined unit of the recording signal, and a level of the recording signal is adjusted.