Fujitsu Corporation

Masaoki Ohtsuka

Teruji Yamakawa

Kiyomi Imamura

Tetsuo Maruyama

Toshiyuki Oi

In an information storage apparatus, a substitution process for substitutionally storing information, when an error occurs in storing the information is prevented from being repeatedly performed with a substitutional area defined in the same recording zone, so that wasteful execution of the substitution process is prevented. The information storage apparatus stores information on a recording medium having a plurality of recording zones, each of the recording zones being divided into a plurality of sectors. A substitutional area is defined in each of the recording zones so as to substitutionally store information when an error occurs in storing the information. A defective sector detecting unit detects a defective sector in each of the recording zones. A control unit controls an operation for storing information so as to store the information, when a number of defective sectors included in a first one of the recording zones is greater than a predetermined value, in the substitutional area of a second one of the recording zones other than the first one of the recording zones in which the information is to be stored. The predetermined number is smaller than a maximum number of defective sectors includable in the substitutional area.

Information storage apparatus for monitoring a number of defective sectors included in a zone so as to select a substitutional area from a different zone

An optical information storage unit optically stores information on a disk shaped recording medium by irradiating a laser beam on the recording medium. The optical information storage unit is provided with a section which controls a laser power of the laser beam irradiated on the recording medium depending on a rotary angle of the recording medium.

Optical information storage unit and laser power control method

An optical memory apparatus, in which an ODC section generates an interruption according to an instruction from an upper system, an ODD section provides drive controls over a memory apparatus according to an interruption by the ODC, and an MPU actuates a timer when an interruption by the ODC is successively generated, invalidates the interruption when a measure time from a time point of generation of a previous interruption until a time point of generation of the last interruption is not over a prespecified period of time, and validates, on the other hand, the interruption when the time measured by the timer is over the prespecified period of time.

Drive control unit and optical memory apparatus

A removable medium data storage apparatus includes a medium loading mechanism for loading a medium, a read circuit for reading data, a buffer for temporarily storing read data, and an MPU. The MPU includes at least a read pattern table for storing a read pattern specified by a read command issued by a host apparatus, the read pattern being formed of a block address and a processed block size, so that data can be prefetched according to the read pattern each time the medium is loaded.

Removable medium data storage apparatus, optical disk apparatus and data

Removable medium data storage with pre-reading before issuance of a

The speed of a write operation in an optical magnetic disk unit is improved by effectively setting the bias magnetic field. When new data is written in an area on a medium, a bias control method for a rewritable storage apparatus which records data by applying a bias magnetic field for data recording and erases recorded data by applying a bias magnetic field for data erasing, applies the bias magnetic field for data erasing to the area to perform an erase operation; applies the bias magnetic field for writing to the area to perform a record operation to record the new data; and applies and maintains the bias magnetic field for data erasing to the medium directly after the record operation is finished.

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Kawasaki, Japan

Masaoki Ohtsuka