Hitachi, Ltd.

Hitachi-Lg Data Storage, Inc.

Hitachi Consumer Electronics Co., Ltd.

Other

Masaaki Kurebayashi

Akihiro Asada

Toshimitsu Kaku

Takashi Hoshino

Yasuhito Tanaka

Hiroyuki Minemura

Tsuyoshi Toda

Koichiro Nishimura

Hidehiko Kando

Hideo Ohnuki

Osamu Kawamae

Makoto Miyamoto

Nobuhiro Tokushuku

Shinji Fujita

Katsuo Konishi

Yoshihiko Noro

Hitoshi Yanagihara

Tetsuya Fushimi

Hideo Oonuki

Hidehiko Kandou

Harukazu Miyamoto

Takeshi Maeda

Motoyasu Terao

Motoyuki Suzuki

Masamichi Yamada

Hitoshi Watanabe

Masayuki Inoue

Shigemi Maeda

Yoshio Suzuki

Norio Ohta

Tetsu Watanabe

Kunikazu Ohnishi

Yukio Fukui

Satoshi Sumi

Toshio Niihara

Yoshie Kodera

Tooru Sasaki

Nobuhide Matsubayashi

Manabu Katsuki

Katsuyuki Tanaka

Toshio Tsuchiya

Masakatsu Saito

Junji Nakajima

Michio Matsuura

Hisamitsu Tanaka

Kouichi Moritani

Naomi Suzuki

A storage system having a plurality of optical disc devices allows other optical disc devices inside the storage system to reproduce the optical disc recorded by a certain optical disc device but inhibits optical disc devices outside the storage system to reproduce the optical disc. A device key as a base for generating an encryption key is common to the plurality of optical disc devices. In the optical disc devices, a guest key other than the device key can be used temporarily to generate the encryption key. An authentication list containing a reproduction condition is recorded with the key information to the optical disc.

Optical disc, optical disc recording method, optical disc reproduction method, optical disc device and storage system

There is provided a method of calculating the degradation over time of the quality of data recorded on an optical disk in a short time. In the method, when user data is recorded on a data area, a test signal including a component in which the signal level is smaller than a reference value, is recorded on a test area. Then, the test signal is reproduced from the test area when a predetermined time has passed, to calculate the quality degradation of the user data from the evaluation result. Alternatively, every time when the user data is recorded/reproduced on/from the data area, the test signal is recorded/reproduced repeatedly on/from the test area. Then, the test signal is reproduced from the test area at a predetermined timing, to calculate the quality degradation of the user data from the evaluation result.

Recording quality evaluation method of optical disk and optical disk storage system

For a disc on which recording is to be performed at a plurality of recording densities, a technique for easily reading out disc management information without an error is disclosed. An optical disc () includes a plurality of data recording areas () for recording information at data recording densities different from each other. Information regarding the data recording densities of the data recording areas () is recorded in a management information recording area (BCA area () or PIC area ()) in a specific format that does not depend on the data recording densities of the data recording areas (). Each data recording area is divided to be arranged on the same surface of the disc, or is divided and arranged on a plurality of recording layers.

Optical disc, optical disc recording/playback apparatus, and information recording/playback method

Recording parameters are decided so that the time control information on at least the front edge and the rear edge of a parameter forming a mark of twice size or above of the laser spot diameter focused on the recording medium is substantially proportional to the recording linear velocity. The mark is recorded and reproduced at a predetermined linear velocity to obtain an electric signal waveform having a time width Tm. A parameter is decided so as to control the laser pulse for recording information so that a voltage value change amount at two points at a distance Ts (Ts&#x3c;Tm/2) in the time axis direction before and after the time position Tm/2 from the front edge of the waveform is substantially constant for the recording linear velocity change. Identification information indicating the parameter is described on the recording medium.

Recording medium, optical disk apparatus and writing method

In an optical disc apparatus, whether an unrecorded recording layer without information recorded thereon is included in the multiple recording layers of the optical disc mounted inside the apparatus is judged. then when the unrecorded recording layer is judged to be present, a signal for focus offset adjustment is recorded in a non-user data recording area of the unrecorded recording layer, and reproduction of the recorded focus offset adjusting signal is followed by its quality evaluation, which is further followed by calculation and setup of an appropriate focus offset value based on evaluation results.

Optical disc apparatus, method of adjusting focus offset for optical disc apparatus, and program for executing focus offset adjustment

An optical disk drive includes drive current generation unit for supplying a mark forming semiconductor laser drive current and a space forming semiconductor laser drive current; first high-frequency superimposition unit for superimposing a high-frequency component on the space forming semiconductor laser drive current; and high-frequency superimposition control unit for controlling the first high-frequency superimposition unit to stop the superimposition of the high-frequency component for a predetermined duration prior to a timing at which to switch from the space forming semiconductor laser drive current to the mark forming semiconductor laser drive current, eliminating positional variations on the disk of the mark leading and trailing edges due to the high frequency superimposition.

High-frequency superimposing method and optical disk apparatus using it

It is an object of the present invention to provide an information recording and reproducing technique capable of improving the reliability of information recorded on a recording medium. A recording condition comprising amplitude information and the ratio of the amplitude to the recording power is previously recorded on the recording medium. Using this previously recorded information, information is recorded and then immediately reproduced to calculate the optimum recording power from the amplitude information obtained from the reproduced signal. By adapting the recording condition accordingly, it is possible to secure reliability of information in performance.

Information recording and reproducing apparatus and information recording medium

According to the present invention, in an optical disk apparatus constructed to supply signals for controlling a semiconductor laser drive circuit provided to an optical pickup from a signal processing circuit through a flexible cable, the semiconductor laser drive circuit is so constructed as to generate a drive current signal for the semiconductor laser on the basis of a binary signal and a clock signal which are supplied from the signal processing circuit through the flexible cable and the signal processing circuit is so constructed as to stop supplying the block signal to the semiconductor laser drive circuit through the flexible cable during reproduction of data, and to start supplying the clock signal to the semiconductor laser drive circuit before recording of data.

Optical disk apparatus wherein recording clock signal is stopped being supplied to semiconductor laser drive circuit on optical pickup during reproduction operation

A laser drive integrated circuit and an optical disk apparatus using the laser drive integrated circuit for forming high-density marks. The optical disk apparatus includes a drive waveform information storage unit for storing at least one information of a drive waveform for driving a laser diode in response to a binary recording signal to be recorded in a recording medium, and a drive waveform decoder for decoding the drive waveform based on the information stored in the drive waveform information storage unit. A recording strategy can be changed in accordance with variations and fluctuations of recording media or characteristics of the recording media, while at the same time reducing a number of signal lines in flexible wiring and alleviating effects of signal distortion in the signal lines.

Laser drive integrated circuit and optical disk apparatus using the same

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Ebina, Japan

Masaaki Kurebayashi