Victor Company of Japan, Limited

Shigeru Nemoto

Kentaro Yokouchi

Kazumi Iwata

Takaro Mori

An optical disc discriminating apparatus has an optical pickup that irradiates a main beam and a pair of sub-beams onto an optical disc to read a signal recorded thereon. The optical pickup has a pair of sub-beam detectors for detecting the sub-beams reflected from the optical disc to generate detection signals. A tracking error signal is produced on the basis of a differential of the detection signals. A type of the optical disc is judged on the basis of comparison between an amplitude of the tracking error signal and a reference amplitude. Or, it is judged on the basis of comparison between an phase difference between the detection signals and a reference phase difference. The judgement under both amplitude and phase comparison is also preferable. The optical pickup conducts tracking servo control on the basis of the detection signals after the judgement is made.

Optical disc discriminating apparatus

A variable transfer rate data reproduction system is provided which performs a reproduction operation and a reproduction inhibit operation cyclically to reproduce data recorded on a recording disc. A pickup traces a spiral track formed on the recording disc during the reproduction operation and is also controlled to continue to trace a following portion of the track over a plurality of track turns during the reproduction inhibit operation without a track jump. Upon resumption of the reproduction operation, the pickup jumps over the plurality of tracks to return back to a portion of the track where the reproduction operation has been Interrupted previously. This results in decreased mechanical stress acting on mechanical parts for moving the pickup.

Variable transfer rate data reproduction apparatus

A variable transfer rate data reproduction system is provided which performs a reproduction operation and a reproduction inhibit operation cyclically to reproduce data recorded on a recording disc. A pickup traces a spiral track formed on the recording disc during the reproduction operation and is also controlled to continue to trace a following portion of the track over a plurality of track turns during the reproduction inhibit operation without a track jump. Upon resumption of the reproduction operation, the pickup jumps over the plurality of tracks to return back to a portion of the track where the reproduction operation has been interrupted previously. This results in decreased mechanical stress acting on mechanical parts for moving the pickup.

An optical disk has regions in which sync signals are recorded. A data detection circuit detects data from a reproduced signal at a timing determined by a data detecting signal. A reproduced waveform of each sync signal is sampled at a first time point, and a first sample value representative thereof is generated. The reproduced waveform of each sync signal is sampled at a second time point different from the first time point, and a second sample value representative thereof is generated. The first and second sample values are compared, and a comparison signal representing a result of the comparing is generated. A phase of the data detecting signal is controlled in response to the comparison signal.

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Yokohama, Japan

Shigeru Nemoto