Hitachi-lg Data Storage, Inc.

Hitachi, Ltd.

Jinya Ikeda

Motoyuki Suzuki

Satoru Moriya

Atsushi Yamada

Shigeki Yamazaki

Toshio Saitoh

Akihiro Ashida

Koji Kaniwa

Tetsuya Fushimi

In an optical disc apparatus, when a signal to be generated corresponding to an amount of reflected light from an optical disc has a signal level below a threshold level for a period exceeding a reference period, a controller controls an actuator to move an objective lens in a direction such that a distance from the optical disc surface to the objective lens increases. The reference period may be set based on a type of the optical disc and a recording or reproducing speed of the optical disc, or based on a surface deflection of the optical disc.

Optical disc apparatus and back off control method for objective lens

A method for adjusting recording power of an optical disk apparatus having an output circuit that outputs recording light onto a test writing area of an optical disk, and a control circuit that adjusts the recording power of the recording light outputted from the output circuit, the method including the steps of causing the control circuit to erase a recording mark recorded onto the test writing area, to record a recording mark onto the test writing area in constant recording power lower than threshold power for starting a recording operation, and to record a recording mark onto the test writing area while changing the recording power.

Method for adjusting recording power and optical disk apparatus

In a three-wavelength-compliant optical disk apparatus, the present invention enables to shorten time required for starting the apparatus such as discrimination of an optical disk and adjustment of a beam-expander. At the time of starting the apparatus, the operation of a tray driver which pulls a loaded optical disk within the apparatus is conducted in parallel with the operation of a beam-expander driver which allows a movable lens of the beam-expander to move to a predetermined position in accordance with the kind of optical disk. Further, at the time of discriminating the disk, the number of times an optical disk of a specific kind has continuously been loaded into the apparatus to date is stored in a memory, and a sequence of discriminating the kind of optical disk that is newly discriminated is switched by referring to the history information.

Optical disk apparatus and starting method thereof

In an embodiment, an optical disk drive includes a land prepit detection circuit. With such circuit, if the optical disk drive reads a poor-quality disk on which, in terms of signals, LPP-like noises are caused by a defect of a land area, it is possible to increase the noise immunity and LPP detection accuracy of the optical disk drive so that the optical disk drive is capable of successfully detecting LPP without fail.

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Kasama, Japan

Jinya Ikeda