Optical Recording Medium Asymmetric Layer Thickness Signal Quality
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Solution Overview
Problem
Optical recording media with multiple information recording surfaces face issues with coherence between reflection lights from different surfaces, leading to degraded servo and reproduction signals due to equal thicknesses between layers, causing back focus problems and interference in signal detection.
Innovation Solution
The optical recording medium is designed with specific thickness conditions where t3−t4≧1 μm, t4−t2≧1 μm, t2≧10 μm, and t1−(t2+t3+t4)≧1 μm, ensuring that the distances between the surfaces are optimized to prevent image formation on the backside and reduce coherence between reflection lights, thereby improving signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If equal thicknesses are used between intermediate layers, then manufacturing is simplified, but coherence between reflection lights from different surfaces causes degraded servo and reproduction signals
Solution Approach 1:
The patent applies asymmetry by setting different thickness values for the first and second intermediate layers. Specifically, the first intermediate layer has a thickness of 10-20 μm while the second intermediate layer has a thickness of 30-50 μm. This asymmetric thickness design prevents coherent superposition of reflection lights from different recording surfaces, thereby eliminating the degradation of servo and reproduction signals while maintaining manufacturing feasibility through clear thickness specifications.
2Reliability
If the distance between the surface and the first information recording surface is increased, then signal deterioration from surface damage or smears is reduced, but the overall disc thickness increases
Solution Approach 1:
The patent applies parameter changes by optimizing the thickness of the first intermediate layer to a specific range of 10-20 μm. This parameter optimization achieves a balance between two competing requirements: it provides sufficient distance from the surface to reduce the impact of surface damage or smears on signal quality, while simultaneously controlling the overall disc thickness by preventing excessive increases. The controlled thickness of the first intermediate layer ensures that the distance between the surface and the first information recording surface is adequate without making the entire disc unnecessarily thick.
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 arrangement enhances the quality of servo and reproduction signals by minimizing interference and allowing for a larger distance between the surface and the first information recording surface, reducing signal deterioration from damage or smears on the optical disc.
Implementation Method 1
coherence between reflection lights from different surfaces
Implementation Method 2
coherence between reflection lights from different surfaces, leading to degraded servo and reproduction signals
Data Source
AI summary
An object of the invention is to provide an optical recording medium and a method for producing an optical recording medium that enable to improve the quality of a servo signal and a reproduction signal. The optical recording medium satisfies: t3−t4≧1 μm, t4−t2≧1 μm, t2≧10 μm, and t1−(t2+t3+t4)≧1 μm, where t1 is a thickness between a surface of the optical recording medium, and the first information recording surface, t2 is a thickness between the first optical recording surface and the second information recording surface, t3 is a thickness between the second optical recording surface and the third information recording surface, and t4 is a thickness between the third optical recording surface and the fourth information recording surface.