Information recording media and optical disc presenting a character or a graphic pattern formed by specified pit patterns on data tracks
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United States of America Patent
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-
Mar 4, 1997
Grant Date -
N/A
app pub date -
Sep 7, 1994
filing date -
Sep 7, 1993
priority date (Note) -
In Force
status (Latency Note)
Importance
Abstract
A CD-ROM is provided with an area for forming a character/graphic pattern. The character/graphic pattern is formed in such a way that data, which generate on the CD-ROM two sorts of pit patterns having average reflectances different from each other to a perceptible extent, are respectively recorded inside and outside the character/graphic pattern. Unless an illegal copy disc is produced by duplicating the legal original disc of the CD-ROM at a very high precision, the character/graphic pattern of the copy disc is invisibly deformed by the discrepancy between the arrangements of the pit patterns of the copy disc and the original disc.
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