Matsushita Electric Industrial Co., Ltd.

Akihiro Hatsusegawa

Katsuya Watanabe

Tatsuo Suzuki

Masanobu Takahashi

Hiroyuki Yamaguchi

Kenji Fujiune

Kouichi Takamine

Yu Okada

A transfer start/end detecting section detects timing at which a DMARQ signal becomes an H level or an L level. A transfer time-measuring section measures a transfer time during which data transfer is actually performed within a period in which a predetermined number of data blocks are transferred. A transfer byte count-measuring section measures a transferred byte count of data that have successfully been transferred. An effective data transfer rate-computing section computes an effective data transfer rate by dividing the transferred byte count by the transfer time. A transfer rate-comparing section compares the effective data transfer rate with a transfer rate that is one step slower than a current transfer rate output from a selectable transfer rate-storing section. If the former is slower, a transfer rate-switching section switches to the transfer rate that is one step slower. A large decrease in the effective data transfer rate caused by data corruption is prevented.

Data transfer device, data transfer system, and data transfer method

A tracking control apparatus comprises an signal processing section, a lens characteristic measuring section and an optimum lens position searching section. The lens characteristic measuring section acquires a first address and second address of an optical disk. The lens characteristic measuring section successively generates offset set values so that the position of a converging lens is moved by an actuator at predetermined spatial intervals and counts the number of times both the first address and the second address are acquired. The optimum lens position searching section searches for a maximum value of the acquisition count and moves the converging lens using the actuator based on the offset set value when the acquisition count reaches a maximum value.

Control apparatus and optical disk apparatus

An optical disc controller for an optical disc drive playing optically a first information storage medium and a second information storage medium having a higher storage density than the first medium. The controller includes: a rotation control section for controlling a rotating mechanism rotating the media; an equalizer for removing first frequency range components from an RF playback signal, obtained by irradiating each media with light and detecting reflected light, and amplifying second frequency range components; and a phase locking section for generating a sync clock signal to do synchronization detection with a digital playback signal obtained by digitizing the output of the equalizer. The rotation control section rotates the media while controlling the rotating mechanism such that RF playback signals are obtained at first and second transfer rates. The maximum playback frequency of the RF playback signal obtained from the first medium at the first transfer rate is substantially equal to that of the RF playback signal obtained from the second medium at the second transfer rate.

Optical disc controller and optical disc device having the same

An optical disc controller for controlling recording or reproduction of an optical disc includes: a rewritable memory for storing information necessary for recording or reproduction of the optical disc; a determination section for determining a class and type of the optical disc; a search section for searching for a region of the optical disc in which control information is recorded based on a determination result of the determination section; a reproduction section for reproducing the control information recorded in the region searched by the search section; and a memory control section for changing an arrangement of the memory based on at least one of the determination result and the control information reproduced by the reproduction section.

Optical disc controller and optical disc apparatus using the same

While discerning whether the laser beam spot is positioned on a land track or a groove track according to the L/G switch signal LGS from the land groove detection unit,, the focus position rough detection unit,and the focus position precise detection unit,detect two new focus positions (for the land and the groove) so that the bit error rate BER that is measured in the error rate measurement unit,and the envelope of and the jitter in the reproduction signal RF would improve, and output two control signals (FBAL and FOFF) for changing the control target position into the new two focus position to the focus error detection unit

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Kyoto, Japan

Akihiro Hatsusegawa