DVD Type Identification via RF Signal Phase Analysis
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Solution Overview
Problem
Conventional methods for determining the type of digital versatile discs (DVDs) are prone to errors due to poor pick-up head quality, variations in reflectivity, and difficulties in reading land pre-pit or address information, leading to inaccurate and time-consuming identification processes.
Innovation Solution
A method utilizing tracking error signals, recorded area (RECD) signals, and total RF level signals to differentiate between ROM, recordable, and re-writable DVDs, which are less affected by optical disc and pick-up head quality, allowing for early identification of ROM DVDs during the servo-on process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional methods use focus error signal amplitude to distinguish re-writable DVDs, then re-writable DVDs can be identified, but determination accuracy deteriorates due to poor pick-up head quality and reflectivity variations
Solution Approach 1:
The patent changes the measurement parameter from focus error signal amplitude to RF level signal characteristics. Specifically, it uses the ratio of RF level signal amplitudes at different phases (in-phase and quadrature-phase components) to determine DVD type, which is less sensitive to pick-up head quality and reflectivity variations.
Solution Approach 2:
The patent replaces the mechanical/optical measurement system (focus error signal based on physical focus positioning) with an electrical signal analysis system (RF level signal phase components), which is more stable and less affected by mechanical variations in the pick-up head.
2Reliability
If conventional methods read land pre-pit or address information to distinguish ROM from recordable DVDs, then DVD type can be determined, but determination time increases due to extensive calibration and tracking requirements
Solution Approach 1:
The patent performs preliminary analysis of the RF level signal characteristics immediately after disc insertion, before full calibration and tracking procedures. By analyzing the in-phase and quadrature-phase components of the RF signal early in the process, it can quickly identify ROM DVDs without requiring time-consuming reading of land pre-pit or address information.
Solution Approach 2:
The patent extracts only the necessary information (RF level signal phase components) needed for DVD type determination, rather than performing complete calibration and reading all disc information. This extraction approach eliminates unnecessary time-consuming steps while maintaining determination accuracy.
3Reliability
If conventional methods use focus error signal with pick-up head movement, then re-writable DVDs can be identified by small amplitude, but measurement precision deteriorates due to pick-up head quality variations
Solution Approach 1:
The patent replaces the mechanical focus error signal measurement system with an electrical RF level signal analysis system. By using the ratio of in-phase to quadrature-phase RF signal components, it eliminates dependence on mechanical pick-up head performance while maintaining the ability to distinguish DVD types.
Solution Approach 2:
The patent changes the measurement parameter from focus error signal amplitude (which varies with pick-up head quality) to RF level signal phase component ratios (which are intrinsic to the disc structure and less affected by hardware variations).
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 method increases determination accuracy and significantly reduces the time required to identify the type of DVD, overcoming the limitations of conventional techniques by using distinct signal amplitudes to reliably distinguish between DVD types without the need for extensive calibration or tracking.
Implementation Method 1
the amplitude of the focused error signal is proportional to the reflectivity of the optical disc
Implementation Method 2
a total RF level signal is read from the optical disc
Data Source
AI summary
A method for determining the type of digital versatile discs (DVDs) is provided, for distinguishing among a read only memory (ROM) DVD, a recordable DVD and a re-writable DVD. The method includes reading a tracking error signal from a DVD. If the amplitude of the tracking error signal is greater than a first predetermined value, the DVD is a recordable DVD; otherwise, a recorded area (RECD) signal is read from the DVD. If the RECD signal is zero, the DVD is a blank re-writable DVD; otherwise, a total RF level signal is read from the DVD. If the total RF level signal is greater than a second predetermined value, the DVD is a DVD ROM; otherwise, the DVD is a re-writable DVD with data.