Disc-shaped optical recordng medium and reproduction limit method thereof

Abstract

There is provided a disk type optical recording medium and a reproduction limitation method for a disk type optical recording medium for preventing illegal copying, etc. to achieve protection of digital contents. A CD is provided which can be reproduced on an ordinary audio CD player but whose readout is impossible at high speed on a CD-ROM drive annexed to a computer. The CD (10) has a clamp hole (14) formed at a position displaced from the central position of a disk substrate (12) with respect to an outer diameter of the disk substrate (12) to form the center of gravity of the disk substrate (12) at a position eccentric by a predetermined amount with respect to the center of rotation provided by the clamp hole. Further, a coating material (16) as a weight for the eccentricity is applied to a label face (10A) of the CD (10). Since the center of gravity and the center of rotation of the CD (10) are eccentric from each other, upon low-speed rotation, stability of rotation can be maintained without being influenced by the eccentricity. However, upon high-speed rotation, the stability of rotation cannot be maintained, resulting in failure in reproduction. Thus illegal copying or the like is prevented to achieve protection of digital contents.

Description

technical field [0001] The present invention relates to a disc-type optical recording medium applicable to various systems, such as CD (Compact Disc) and DVD (Digital Laser Video Disc), and to a reproduction limitation method for the disc-type optical recording medium. Background technique [0002] For example, CDs dedicated to music information have become widespread these days, and various kinds of music can be reproduced with CD players dedicated to CDs. In this case, digital information of a CD reproduced by a CD player is actually converted into an analog sound signal, and output to a speaker, a tape recorder, or the like. [0003] Meanwhile, CD-ROMs or CD-Rs for data processing mainly used by computer peripherals, which are used to store or record data processed by computers through various disk drives, have been provided. In this case, the information of the CD-ROM or CD-R is handled as digital information. [0004] By the way, with the popularization of various com...

AI Technical Summary

Problems solved by technology

[0005] In addition, although it is convenient to extract the music information of the CD as digital data without loss in this way, the problem of copyright protection has arisen and become a major social problem

Specifically, with the promotion of network broadband communication not only in distributing or selling CD-Rs containing exactly the same content as the original CD to unrelated people but also in distributing favorite music contained in CDs to unrelated people through the network , the problem becomes more serious

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