Ag-Alloy Reflective Film for Optical Disc Anti-Piracy
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Solution Overview
Problem
Current optical recording media fail to effectively distinguish and prevent the reproduction of pirate versions, as existing methods for recording identity information on reflective films can lead to thermal expansion issues and unauthorized copying of main and sub-data during the physical copying process.
Innovation Solution
An optical recording medium with a reflective film made from an Ag-alloy film containing elements like Ti, W, Ta, V, Mo, Nb, and Zr, where the composition of these elements is specifically chosen to increase the reproducing signal level for normal versions while decreasing it for pirate versions, allowing for the reversal of sub-data polarities and detection of illegal copies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If a mark is formed on the reflective film by laser irradiation to record identity information, then the reflectance changes to encode sub-data, but thermal expansion occurs and enables physical copying of the mark
Solution Approach 1:
The patent changes the material composition parameter of the reflective film by using Ag-alloy films with specific elements (Ti, W, Ta, V, Mo, Nb, Zr) in controlled concentrations. This material parameter change creates differential thermal expansion characteristics between normal and pirate version discs, enabling detection while preventing harmful thermal effects from compromising security
Solution Approach 2:
The patent applies local quality by creating specific compositional variations in the Ag-alloy reflective film at different locations or layers. The alloy contains multiple elements with different concentrations or distributions, creating localized properties that affect thermal expansion differently in legitimate versus copied discs, thereby preventing unauthorized reproduction
2Reliability
If the reproducing signal level is increased for normal versions, then copyright protection is enhanced, but the same signal level increase would allow pirate versions to be reproduced
Solution Approach 1:
The patent inverts the approach by making pirate version discs produce degraded or inverted reproducing signals compared to normal versions. Instead of trying to prevent pirate discs from being created, the system ensures that when pirate discs are reproduced, the signal level is fundamentally different (lower or inverted polarity), making the pirate content unusable while maintaining normal reproduction for legitimate discs
3Productivity
If a stumper is produced by mastering process to create replica versions, then production efficiency is improved, but copyright infringement occurs
Solution Approach 1:
The patent applies the copying principle in reverse by creating a master disc with specific Ag-alloy reflective film properties that cannot be accurately copied through conventional mastering processes. The complex multi-element alloy composition creates thermal expansion characteristics and optical properties that are difficult to replicate, thereby preventing pirate stumper production while allowing legitimate high-volume production through injection molding
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 the optical recording medium to reliably differentiate between normal and pirate versions by altering the reproducing signal levels, effectively preventing the reproduction of pirate versions and ensuring copyright protection.
Implementation Method 1
a reflective film and a cover layer are stacked and formed on a substrate; sub-data are recorded by a mark that is formed by the irradiation of laser light for the write-once recording with respect to the reflective film
Implementation Method 2
a write-once recording is made to be possible on the reflective film by thermal-recording by irradiating a laser light
Data Source
AI summary
An optical recording medium is provided. The optical recording medium includes at least a reflective film and a cover layer on a substrate; main data by a combination of pit and land are recorded on the substrate; a write-once recording is made to be possible on the reflective film by irradiating a laser light; sub-data are recorded by a mark that is formed by the irradiation of laser light for the write-once recording with respect to the reflective film; a reproducing signal level at portion where said mark is formed increases for the land of specified length; the mark by which the reproduced level decreases at the portion where the mark is formed is formed for an optical disc recording medium manufactured by physical copy; the reflective film is composed of an Ag-alloy film of Ag100-xXx(0<x<100); and the X is selected from Ti, W, Ta, V, Mo, Nb and Zr.