Optical Disc Defect Detection and Recording Range Control
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Solution Overview
Problem
Optical discs with thinner light transmitting layers, such as Blu-ray discs, are prone to large-scale defective areas due to bubbles formed during manufacturing, which can cause data read/write errors and inefficient recording processes due to warped light transmitting layers and spherical aberration, leading to wasted storage capacity and potential data loss.
Innovation Solution
An optical disc apparatus that detects and measures defective areas, such as those caused by bubbles, before data writing, allowing for the management of storage areas to avoid these defects, ensuring data is written only on non-defective regions by determining the size and location of defective areas and adjusting the recording range accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a spin coating process is used to form a protective coating on the optical disc, then the coating can be applied effectively, but bubbles are trapped between the light transmitting layer and the substrate, producing large-scale defective areas
Solution Approach 1:
The patent performs a surface check before data recording to detect defective areas caused by bubbles. By identifying these areas in advance and excluding them from the recording range, the system prevents data loss without requiring changes to the manufacturing process itself.
Solution Approach 2:
The patent converts the harmful effect of bubbles into a manageable issue by detecting the defective areas they create and using this information to adjust the recording range. The presence of bubbles, while harmful, provides detectable signals that allow the system to adaptively avoid defective regions.
2Quantity of substance
If the light transmitting layer is made thinner to increase storage density, then higher storage capacity is achieved, but the layer becomes more susceptible to warping and bubble formation
Solution Approach 1:
The patent implements dynamic adjustment of the recording range based on detected defective areas. The system adapts the recording strategy in real-time by excluding identified defective regions from the recording plan, allowing flexible utilization of available storage space while maintaining reliability.
Solution Approach 2:
The patent uses feedback from the surface check process to inform subsequent recording operations. The detection results about defective areas are fed back into the recording range determination, creating a closed-loop system that continuously optimizes data storage reliability based on actual disc conditions.
3Productivity
If data recording proceeds without checking for defective areas, then recording speed is maintained, but data loss occurs due to writing on defective areas
Solution Approach 1:
The patent performs a surface check before data recording to detect defective areas. By identifying these areas in advance and excluding them from the recording range, the system prevents data loss without requiring changes to the manufacturing process itself.
4Reliability
If the recording range is reduced to avoid defective areas, then data loss is prevented, but storage capacity utilization decreases
Solution Approach 1:
The patent implements dynamic adjustment of the recording range based on detected defective areas. The system adapts the recording strategy in real-time by excluding identified defective regions from the recording plan, allowing flexible utilization of available storage space while maintaining reliability.
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 smooth data writing operations by avoiding defective areas, improving real-time recording performance, reducing the likelihood of data loss, and optimizing storage capacity utilization by preventing unnecessary waste of available space.
Implementation Method 1
Irradiating the storage layer with a light beam from an optical pickup, the present invention has made it possible to detect a defective area
Data Source
Figure 1(a)~1(b)
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AI summary
It is determined whether an error will occur due to presence of a defective area like a bubble and the storage area is managed according to the size of the defective area such that no data is written on the defective area once an error has occurred. An optical disc apparatus includes: an optical pickup for irradiating an optical disc with a light beam and generating a light detection signal on the beam reflected from the disc; a search section for searching, before data is written there, the storage area on the disc for any defective area by controlling the pickup to shift the light beam spot on the disc; a defect decision section for determining, if an error has been detected based on the light detection signal, a part of the storage area where the error has occurred to be a defective area; a size measuring section for measuring the size of the defective area and generating a defect information list to locate the defective area; and a recording range control section for managing the storage area by reference to the defect information list such that no data is written on the defective area.