Optical disc, device for checking optical disc and device for re

Details Optical disc, device for checking optical disc and device for re Optical disc, device for checking optical disc and device for re

1996-09-23

1997-12-09

Dinh, Tan

Dynamic information storage or retrieval

Storage medium structure

Optical track structure

369 58, G11B 724, G11B 390

Patent

active

056967578

ABSTRACT:
An optical disc on which a number of spiral trains of regular pits and at least one train of irregular pits are formed. The regular pits of each of the trains is arranged symmetrically with respect to the center of a track. Each of the irregular pits has a predetermined shape different from a shape of each of the regular pits. An arrangement of the train of the irregular pits being differs from an arrangement of each of the trains of the regular pits. A tracking error signal being obtained from the train of the irregular pits. An irregular pit can not be copied even when a normal optical disc containing such an irregular pit is copied by performing a conventional copying method. Thus, an illegal copy disc can be discriminated from a normal optical disc by checking whether or not an irregular pit is included in an optical disc to provide good copy protection by easily detecting an illegal copy disc.

REFERENCES:
patent: 4849836 (1989-07-01), Kaghikian
patent: 4879704 (1989-11-01), Takagi et al.
patent: 5428598 (1995-06-01), Veldhuis et al.
patent: 5432647 (1995-07-01), Tateishi
patent: 5453968 (1995-09-01), Veldhuis et al.
patent: 5461220 (1995-10-01), Ogino
patent: 5572507 (1996-11-01), Ozaki et al.

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