Hitachi, Ltd.

Kouichi Moritani

Nobuhiro Tokushuku

Masaaki Kurebayashi

Yoshie Kodera

Katsuyuki Tanaka

Katsuo Konishi

Yoshihiko Noro

Hitoshi Yanagihara

A video optical disk system which can record/reproduce information in the same recording format as that of a read only type optical disk such as an LD, and is therefore compatible with both the read only type optical disk and a writable optical disk. A writable optical disk exhibiting a C/N ratio of at least 60 [dB] is employed, and has information recorded thereon with the same address signals as those of the LD and in the NTSC direct FM recording format. An optical head and an image processing circuit which are included in a player unit are made common to the recorded disk and the LD, and characteristics of a focusing/tracking control circuit, an RF signal preamplifier circuit and a tilt control circuit which are included in the player unit are changed over on the basis of reflectances of both types of optical disks, thereby enabling both the recorded disk and the LD to be reproduced. The users of the optical disk system can produce original video software by themselves, and can effectively utilize a software stock of read only type optical disks.

Video optical disk system compatible with both read only and writable

Growing community of inventors

Yokohama, Japan

Kouichi Moritani