Opposite Track Paths for Multilayer Optical Discs
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Solution Overview
Problem
In two-layer type information recording media, uninterrupted reproduction is challenging due to the need to change the optical pickup's position from the outer to the inner circumference during layer changes, and the OPC process is time-consuming when performed collectively for both layers.
Innovation Solution
The information recording medium and apparatus feature a first recording layer with a test writing area on the inner circumference and a recording area on the outer circumference, and a second layer with a test writing area on the inner circumference and a recording area on the outer circumference, allowing for opposite direction track paths and efficient test writing and recording without requiring significant buffer storage or lengthy layer changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the track paths in both recording layers are arranged in the same direction (parallel type), then the structure is simple and easy to manufacture, but the optical pickup must return from the outer circumference to the inner circumference during layer changes, causing interruptions and requiring huge buffer storage
Solution Approach 1:
The patent applies inversion by arranging the track paths in opposite directions between layers. Specifically, the first recording layer uses a track path from the inner circumference to the outer circumference, while the second recording layer uses a track path from the outer circumference to the inner circumference. This allows the optical pickup to continue moving in the same rotational direction when changing layers, eliminating the need to return to the starting position and enabling uninterrupted reproduction.
2Productivity
If the OPC process is performed collectively for both recording layers, then the calibration is efficient, but the optical pickup must be displaced from the inner circumference to the outer circumference, taking extremely long time
Solution Approach 1:
The patent segments the OPC (Optimum Power Calibration) process into separate operations for each recording layer. The first OPC process is performed on the first recording layer at the inner circumference, and the second OPC process is performed on the second recording layer at the outer circumference. This segmentation allows the calibration processes to be independent and eliminates the need to move the optical pickup across the entire disc diameter during layer changes.
Solution Approach 2:
The patent performs the OPC process as a preliminary action before the actual recording operation. By completing the calibration for each layer in advance at its respective position, the system prepares the optimal recording power settings beforehand, so that when recording begins, no time-consuming adjustments or movements are needed during the actual data recording phase.
3Loss of time
If the OPC process is performed separately for each recording layer, then the layer change time is reduced, but the overall recording time increases due to multiple calibration operations
Solution Approach 1:
The patent ensures continuity of useful action by arranging the track paths in opposite directions and positioning the PCA areas at opposite ends of the disc. This configuration allows the optical pickup to perform the OPC process for the first layer, immediately record data on the first layer, then transition to the second layer for its OPC process and recording, all without idle movements or interruptions. The useful actions (calibration and recording) continue seamlessly across layer 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 configuration enables quick and uninterrupted reproduction by eliminating the need for significant buffer storage and reducing the time required for layer changes and test writing, facilitating efficient recording and reproduction on multilayer optical discs.
Implementation Method 1
the information is recorded into a recording layer (referred to as a 'L0 layer' in this application), located on the front or the closest side as viewed from the emission or irradiation side of laser light, in a rewritable method or irreversible change recording method by irreversible change recording heat by using heat or the like, by focusing the L0 layer with the laser light for recording
Implementation Method 2
by focusing the L0 layer with the laser light for recording
Data Source
AI summary
A disc-shaped information recording medium includes a first recording layer (L0 layer) having (I) a first trial write area (101P-1) for trial write of first trial write information for calibration of the laser beam along the first track path (TP1) from the inner circumference toward the outer circumference and (II) a first recording area for recording the first recording information along a first track path (TP1), in this order from the inner circumference side. Furthermore, the disc-shaped information recording medium includes a second recording layer (L1 layer) having (I) a second trial write area (101P-2) for trial write of second trial write information for calibration of the laser beam along the second track path (TP2) from the outer circumference toward the inner circumference and (II) a second recording area for recording the second recording information along a second track path (TP2), in this order from the inner circumference side.