Multilayer Optical Disc Management Area for Layer Access
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Solution Overview
Problem
Multilayer optical discs with information layers conforming to different standards face challenges in quickly accessing and identifying the presence and type of other information layers, leading to increased access time when switching between layers.
Innovation Solution
Incorporating a management area in the information layer with the highest recording density to record information about the presence and type of other information layers, allowing the optical disc device to efficiently identify and access them by pre-setting laser power and tracking error signal methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a multilayer optical disc has information layers conforming to different optical disc standards, then the disc can accommodate multiple standards and increase user convenience, but it takes time to access other information layers when the need to reproduce or record information on another layer suddenly arises
Solution Approach 1:
The patent applies preliminary action by recording management information about other information layers in advance in the management area of the highest-density layer. This pre-stored information includes the presence, type, and location of other layers, allowing the optical disc device to immediately access and utilize this information when switching layers, thereby eliminating the time delay that would otherwise occur during layer transitions.
2Device complexity
If the type of one information layer is not recorded on another layer, then the disc structure remains simple, but every time the device accesses a different information layer, it must read the type of the layer to select a method of generating a tracking error signal, which increases access time
Solution Approach 1:
The patent applies copying by creating a copy of the management information (including layer types and tracking methods) in the management area of the highest-density information layer. This copy allows the optical disc device to retrieve layer type information immediately without needing to read it from each individual layer during access operations, thus reducing access time while maintaining relatively simple disc structure.
3Loss of time
If information indicating the types of other information layers is recorded in a management area of the highest-density layer, then access time is reduced by enabling quick identification of layer types, but the disc structure becomes more complex
Solution Approach 1:
The patent applies universality by utilizing the management area of the highest-density information layer, which is already a necessary component of the disc structure, to serve multiple functions: both managing the highest-density layer itself and storing management information about all other information layers. This multi-functional use of the existing management area reduces the need for additional separate management structures, thereby minimizing the increase in overall disc structure complexity while achieving fast access times.
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 solution significantly reduces access time by enabling the optical disc device to quickly determine the type and presence of other information layers, optimizing access and recording operations.
Implementation Method 1
In a CD (compact disc), the thickness of the disc substrate used as a light transmitting layer is about 1.2 mm, the wavelength of the laser beam is about 780 nm... In a DVD (digital versatile disc), the thickness of the disc substrate used as a light transmitting layer is about 0.6 mm, the wavelength of the laser beam is about 650 nm... For a BD (Blu-ray disc) disc having a still higher density uses an optical disc having a protection layer as thin as 0.1 mm as the light transmitting layer on the optical recording layer. With a laser beam wavelength of about 405 nm
Implementation Method 2
by using objective lenses with higher numerical apertures, and by reducing the size of the focused light spot on the focal plane
Data Source
AI summary
In a multilayer optical disc having information layers conforming to a plurality of different optical disc standards, because the type of each information layer is not recorded in the other information layers, in read and write operations by a compatible optical disc device conforming to a plurality of optical disc standards, every time the information layer being accessed changes, it has been necessary to read the type of the information layer and select a method of generating a tracking error signal adapted to the type of information layer, so access has taken time. In order to solve the above problem, in the optical multilayer disc according to the present invention, having information layers conforming to a plurality of different optical disc standards, in an area in one of the information layers, information about the other information layers is recorded. The time required to access the other information layers can be reduced by using this information to select a tracking error signal generating method.