Multilayer Disc Recording Power Control via L0 Layer State Detection
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Solution Overview
Problem
In multilayer optical discs, efficiently recording information onto the second layer (L1) is hindered by irregular recorded and unrecorded states in the first layer (L0), leading to non-uniform reproduction quality and increased recording time due to the need for complex power adjustments.
Innovation Solution
An information recording apparatus and method that uses specific laser powers (44 mW and 46 mW) based on the reproduction quality changes caused by mixed recorded and unrecorded states in the L0 layer, allowing for efficient recording by judging the unrecorded area size and controlling the recording process to minimize waste and ensure consistent quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If recording power is adjusted to appropriately perform recording when L0 layer is in recorded state, then reproduction quality in recorded areas is improved, but reproduction quality in unrecorded areas deteriorates
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the laser recording power based on the detected state of the L0 layer. When the L0 layer is determined to be in a recorded state, the recording power is increased to 44mW to achieve appropriate asymmetry values and good reproduction quality. When the L0 layer is in an unrecorded state, the recording power is reduced to 46mW to prevent excessive asymmetry values and maintain signal quality. This dynamic parameter adjustment resolves the contradiction between optimizing reproduction quality in recorded areas and maintaining uniformity across unrecorded areas.
2Manufacturing precision
If complex power adjustments are made to handle mixed recorded and unrecorded states, then reproduction quality uniformity is improved, but recording time increases
Solution Approach 1:
The patent applies preliminary action by performing a preliminary detection of the L0 layer state before executing the recording operation on the L1 layer. The system detects whether the L0 layer is in a recorded or unrecorded state in advance, stores this information, and then selects the appropriate recording power (44mW or 46mW) before actual recording begins. This preliminary detection and power selection approach allows the system to maintain reproduction quality uniformity without requiring complex real-time power adjustments during recording, thereby preserving recording speed and productivity.
3Productivity
If recording is performed without considering L0 layer state, then recording speed is improved, but reproduction quality becomes non-uniform
Solution Approach 1:
The patent applies feedback by using the detected state of the L0 layer to control the recording power for L1 layer recording. The system continuously monitors the L0 layer state through detection signals, and this feedback information is used to automatically adjust the laser recording power to either 44mW or 46mW. This feedback mechanism ensures that reproduction quality remains uniform across both recorded and unrecorded areas of the L0 layer, while maintaining efficient recording speed by avoiding unnecessary complex control operations.
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 quick and efficient recording on multilayer discs by minimizing the impact of irregular states in the L0 layer, reducing recording time, and maintaining uniform reproduction quality without the need for frequent power adjustments.
Implementation Method 1
laser light for recording is focused or condensed on a recording layer located on the front (i.e. on the closer side to an optical pickup) as viewed from the irradiation side of the laser light
Implementation Method 2
laser light for recording is focused or condensed on a recording layer
Implementation Method 3
record information into the L0 layer in an irreversible change recording method by heat
Data Source
AI summary
In an information recording medium including at least a first recording layer (L0 layer) capable of recording information and a second recording layer (L1 layer) capable of recording information, an information recording device (300) records information in a predetermined area (12) of the second recording layer by a laser beam which has passed through a transmission area (11) of the first recording layer. The information recording medium (300) includes recording means (302, etc.) for recording the information in the first recording layer or the second recording layer, judgment means for judging whether an unrecorded amount indicating the size of the unrecorded area in the radial direction in the transmission area is smaller than a predetermined amount, and control means used when the unrecorded area is judged to be smaller than the predetermined amount, for controlling the recording means to record information in the predetermined area.