Optical disk including a barcode pattern formed by a laser using pulse width modulation

Abstract

An object of the present invention is to provide a marking forming apparatus, a method of forming a laser marking on an optical disk, a reproduction apparatus, an optical disk, and a method of manufacturing an optical disk, capable of providing a greatly improved copy prevention capability as compared to prior known construction. To achieve this object, in the optical disk of the invention, for example, a marking is formed by a laser on a reflective film of a disk holding data written thereon and at least position information of the marking or information concerning the position information is written on the disk in an encrypted form or with a digital signature appended thereto.

Description

[0001]This is a Reissue Divisional Application of U.S. patent application Ser. No. 09 / 588,364, filed Jun. 2, 2000, which is a Reissue Application of U.S. Pat. No. 5,761,301, issued Jun. 2, 1998.[0002]More than one reissue application has been filed for the reissue of U.S. Pat. No. 5,761,301. The reissue applications are U.S. application Ser. No. 10 / 183,205 (the present specification), Ser. Nos. 10 / 020,427, 10 / 017,973, 10 / 017,965, and 09 / 588,364, all of which are divisional reissues of U.S. Pat. No. 5,761,301.BACKGROUND OF THE INVENTION[0003]1. Field of the Invention[0004]The present invention relates to a marking forming apparatus, a method of forming a laser marking to an optical disk, a reproduction apparatus, an optical disk, and a method of manufacturing an optical disk, which may be utilized, for example, to prevent duplication of optical disks.[0005]2. Description of the Prior Art[0006]With increasing use of ROM-type optical disks in recent years, pirated disks have also been ...

AI Technical Summary

Benefits of technology

This approach significantly improves piracy prevention by making it difficult to replicate disks with high accuracy, securing password protection, and allowing legitimate manufacturers to produce disks without specialized equipment, thereby reducing financial losses and expanding production capabilities.

Problems solved by technology

With increasing use of ROM-type optical disks in recent years, pirated disks have also been spreading, infringing the rights of copyright owners.

This necessarily means a financial loss to the copyright owner.

However, since it is possible to extract this physical mark by examining a legitimate disk, the prior art method has had the problem that pirated disks may be made if such a special mastering apparatus falls into the hands of an illegal person.

This method requires much time and cost to produce one master disk, but since hundreds of thousands of disks can be produced from one pirated master disk, the cost per pirated disk is low.

This has therefore given rise to the problem that as the replica method becomes widespread in the future, it may defeat the effectiveness of piracy prevention techniques at the master disk level.

As described above, the prior art piracy prevention techniques have several problems to be overcome.

Problem 1: The effectiveness of the master disk level piracy prevention techniques of the prior art is low since it is possible to replicate the physical mark.

Problem 2: In the prior art method that forms a physical mark based on physical mark design data, if a manufacturing apparatus of the same precision as the apparatus used by the legitimate disk manufacturer is obtained, illegal disks can be easily manufactured.

Problem 3: Since the security level provided by the prior art piracy prevention methods is fixed, its effectiveness decreases against constantly improving pirating techniques.

The use of copy protection is therefore limited to closed specifications such as game disks.

Problem 5: According to the prior art methods, a limited number of licensing companies possess the special manufacturing apparatus and do not make the apparatus public.

Therefore, software makers cannot make disks except at the licensing companies.

As a result, password security cannot be maintained unless a floppy disk or a communication line is used in combination.

Furthermore, the password has to be entered each time the disk is used since secondary recording is not possible.

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