Dynamic information storage or retrieval – Condition indicating – monitoring – or testing – Including radiation storage or retrieval
Reexamination Certificate
1999-01-20
2001-10-16
Tran, Thang V. (Department: 2753)
Dynamic information storage or retrieval
Condition indicating, monitoring, or testing
Including radiation storage or retrieval
Reexamination Certificate
active
06304535
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a disc discriminating device in a disc playback apparatus.
Recently, various kinds of discs have been developed and, particularly, a digital video disc (DVD) that has the same outer size as that of a well-known audio compact disc (CD) but seems hardly distinguished therefrom has been developed. In addition, a disc playback apparatus having compatibility so as to realize the playback corresponding to any disc loaded into the apparatus, has been also developed. Accordingly, when the playback apparatus is loaded with a disc, the kind of the disc needs to be discriminated.
As for discrimination of the disc type, various kinds of methods have been proposed, such as a method of preliminarily recording distinction signals in a disc and reading them, a method of setting the playback apparatus in a predetermined mode, reading signals from the disc and discriminating whether or not the signals are normal, and the like.
According to a conventional disc discriminating method, a comparatively complicated structure is required and it is expensive. In addition, much time have to be spent for the disc discrimination.
BRIEF SUMMARY OF THE INVENTION
The object of the present invention is to provide a disc discriminating device in a disc playback apparatus, which can be realized with a comparatively simple structure and spends a short time for disc discrimination.
In order to achieve this object, in the present invention, focus servo control is operated to rotate a disc at a constant linear velocity, and the rotation number of the disc motor is measured so that the kind of the disc can be discriminated.
Another object of the present invention is to discriminate the kind of the disc by rotating the disc in a state of operating the focus servo control and counting the number of tracks which a pickup crosses.
A yet another object of the present invention is to employ an optical pickup in a three-beam system, generate tracking error signals by the read output of a subbeam and thereby discriminate the kind of the disc in response to the level of the signal.
Further, the other object of the present invention is to discriminate the kind of the disc by operating the focus servo control to rotate a disc at a constant linear velocity and monitoring tracking errors, i.e., cross talks.
Moreover, the other object of the present invention is to discriminate the kind of the disc by employing an optical pickup in the push/pull detecting system and monitoring the level of tracking error signals.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.
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patent: 4653040 (1987-03-01), Senso
patent: 5644561 (1997-07-01), Son et al.
patent: 5745460 (1998-04-01), Tateishi
patent: 5764610 (1998-06-01), Yoshida et al.
patent: 5974014 (1999-10-01), Tajiri
patent: 6141307 (2000-10-01), Yoshioka
patent: 1098161 (1989-04-01), None
patent: 4067463 (1992-03-01), None
patent: 10302380 (1998-11-01), None
Kon Yoshitaka
Magome Takahiro
Kabushiki Kaisha Toshiba
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Tran Thang V.
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