Hitachi-Lg Data Storage, Inc.

Akihiro Ashida

Motoyuki Suzuki

Satoru Moriya

Kikuo Shimizu

Kouji Fukuda

Takashi Nagai

Shinsuke Takatsuka

Koji Kaniwa

Jinya Ikeda

Ryuta Aihara

Hisanobu Tajima

Yuuki Yamasaki

A disk conveyance unitconveys the disk mediumto a position where recording and reproducing are performed by the pickupwith the spindle motorheld. The disk conveyance unitincludes first movement mechanismsandfor moving a first conveyance framewith respect to fixed framesandand second movement mechanismsandfor moving a second conveyance frameholding a spindle motorwith respect to the first conveyance frame. The first and second movement mechanisms move to substantially the same direction and operate independently from each other. This allows the disk of the hologram recording and reproducing apparatus to be moved at a high speed and positioned at a high accuracy.

Hologram recording and reproducing apparatus

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

An optical disc device and tracking control method capable of stable tracking control even for inferior optical discs with tracks decentered by a large amount. The optical disc device and tracking control method includes: obtaining a rotation angle at which the degree of displacement of the track due to the eccentricity of the optical disc becomes maximum on the inner circumference side and the outer circumference side, and detecting the eccentricity amount of the optical disc; and performing track pull-in at the rotation angle, at which the degree of displacement of the track due to the eccentricity of the optical disc becomes maximum, detecting a displacement direction of the optical disc at the time of the pull-in, and moving the slider in the detected displacement direction for a distance equal to or almost equal to the eccentricity amount of the optical disc.

Optical disc device and tracking and slider control method

This invention provides an optical disc device that can prevent the occurrence of an error in a starting position of a write operation due to off-tracking, and to avoid an unnecessary stop of the write operation during writing. A tracking error signal generator generates a tracking error signal from a signal which has been detected by an optical pickup, and a system controller detects off-tracking by comparing the tracking error signal with a threshold level, and turns control operation of a tracking servo controller off if the threshold level is exceeded. The off-tracking detection threshold level applied during a time period from completion of seek operation to a start of movement of the optical pickup to the starting position of the write operation is set to be lower than a threshold level applied during a time period of data recording.

Optical disc device and tracking control method

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Tokyo, Japan

Akihiro Ashida