Yamaha Corporation

Akio Hirai

Kenichiro Takeshita

Morihiro Murata

An optical disk is compatible with one type of a recording apparatus which is designed to irradiate an optical beam onto the optical disk to form pits along the pregroove for actual recording of information. The optical disk is incompatible with another type of a recording apparatus which is designed to successively record the times of the test recording into a count area of the conventional optical disk. The optical disk has a test area corresponding to the test area of the conventional optical disk and a prepit area corresponding to the count area of the conventional optical disk, the prepit area being provisionally formed with prepits at least in a section corresponding to the predetermined section of the count area of the conventional optical disk so as to inhibit the other type of recording apparatus from conducting the test recording.

Optical disk capable of disabling incompatible recorder

Each data read out from an optical disk is written into a RAM in response to a reproduced clock signal and then read out from the RAM in response to a reference clock signal. A decoder circuit detects a Run-out block in a data link period of the read-out data. Once such a Run-out block is detected, a timing resetting circuit compulsorily moves write and read pointers to the RAM to middle address and first address locations, respectively, of the RAM, so as to restore a distance between the two pointers to a predetermined basic distance corresponding to substantially half the total number of addresses of the RAM. With this arrangement, it is possible to avoid an overflow or underflow in the RAM that would result from the clock reproduction getting out of phase-locking by a phase locked loop during optical scanning in a data link period.

Growing community of inventors

Hamamatsu, Japan

Akio Hirai