Sony Corporation

Koichiro Ogihara

Shoei Kobayashi

Tamotsu Yamagami

Toru Takeda

Masaki Uchida

A device includes: an objective lens that serves as a lens having a first numerical aperture when a first optical beam corresponding to a first optical disc converges on the first optical disc while serving as a lens having a second numerical aperture when a second optical beam corresponding to a second optical disc converges on the second optical disc; a section that generates a reflection optical signal from the first or second optical beam reflected by the first or second optical disc; and a section that determines whether an unknown disc is the first optical disc based on a degree of matching between the waveform of the reflection optical signal obtained when the first optical beam is emitted to the first optical disc, and the waveform of the reflection optical signal obtained when the first optical beam is emitted to the unknown disc.

Optical disc device and media type determination method

An optical disc recording method and apparatus is capable of overwriting a phase change optical disc at high speed. With a preceding erasing beam out of two laser beams, a modulation component in an RF signal recorded on an optical disc is erased to a state where no problem occurs (the reflectance difference is reduced) and the top level is decreased to 70 to 40% of a top level of an original RF signal. After that, with the subsequent recording beam, a space is recorded at a laser power at which top level is reset to the original state (before the erasing process), and a mark is recorded at a laser power which can sufficiently decrease the bottom level. Consequently, even when the recording speed is the quadruple speed (about 1.6 to 2 times of a specification) much higher than a specific recording speed (for example, 2 to 2.4&#xd7;) of a phase change optical disc, overwriting can be performed with a recording characteristic which can satisfy a regenerating characteristic specification.

Optical disc recording method and apparatus

The present invention is applied to an optical disk apparatus which records data on and/or plays back data from one of a variety of DVD optical disks. The present invention generates a binarization threshold Sby offsetting an envelope Sof a playback signal RF by an offset voltage V, and binarizes the playback signal RF (S) according to the binarization threshold.

Multi-format optical disk device and optical disk recording and/or reproducing method

The frequency components of the groove wobbles of disks are extracted from push-pull signals Sby first and second filters in a wobble detecting section. The wobble detecting section supplies to the controller the detection levels of the frequency components. The controller identifies the kind of the mounted optical disks based on the detection levels.

Optical disk drive, and method for identifying optical disks mounted thereto

Optical recording medium and recording method thereof

A disc drive unit in which a controller detects the storage capacity of the disc cartridge during loading into the drive by interrogating switches which are actuated by capacity indication markers on the disc cartridge.

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Tokyo, Japan

Koichiro Ogihara