Kabushiki Kaisha Toshiba

Nec Corporation

Hideaki Ohsawa

Chosaku Noda

Yutaka Yamanaka

Hiroharu Satoh

Kinji Kayanuma

Akihito Ogawa

Kazuto Kuroda

Minoru Yonezawa

Hiroharu Sato

Kazuo Watabe

Yuji Nagai

Hisashi Yamada

Naomasa Nakamura

Naoki Morishita

Masatsugu Ogawa

Ryuichi Katayama

Toshihiko Kaneshige

Sumitaka Maruyama

Toshiaki Iwanaga

Masahiko Tanaka

Nobuhisa Yoshida

Maho Kuwahara

Daisuke Eto

Takeharu Shibatoko

Nobumasa Naito

According to one embodiment, a first encoder encodes main information, a second encoder encodes sub-information, a first modulator modulates a carrier based on an output of the first encoder, a duplicating module duplicates an output of the second encoder to generate encoded sub-information units, and a second modulator amplitude-modulates an output of the first modulator based on the encoded sub-information units. The second modulator amplitude-modulates with &#x3c3;/(&#x3bc;&#xd7;(2)) being 0.4 or less, wherein a noise power of a transmission path or a storage medium is &#x3c3;, a number of the encoded sub-information units is N, signal levels after amplitude modulation, which correspond to bitand bitof the encoded sub-information units, are A and B, and a level difference A&#x2212;B is &#x3bc;.

Signal processing system and information storage medium

The length of a format modulation area in an address segment is limited to be 25% of the address-segment length or less, and the position of the format modulation area is selectable two possible positions. Subsequently, where a CLV optical-disk medium is used, wobble modulation areas in adjacent recording tracks do not overlap each other in the radius direction.

Optical disk medium and optical disk apparatus

In an optical disk medium, land recording tracks () are coupled by first and second coupling portions (and) at a particular radial position to form a tilt detecting mark SM.

Optical disk medium and optical disk recording/reproducing apparatus utilizing tilt detection areas having special marks

This invention relates to a focus control apparatus having a controller which generates a control signal and performs focus operation when the peak timing of a focus sum signal based on reflected light and the zero-crossing timing of a focus error signal are detected to substantially coincide with each other in supplying a control signal to a lens actuator driver for supplying a driving signal to a lens actuator for driving a lens. The invention also relates to an optical disk apparatus using the focus control apparatus. By detecting coincidence of the two timings, two reflected waves are discriminated, and stable focus operation is achieved.

Layer discriminating focus control apparatus, optical disk apparatus, and methods therefore

A recording data string is composed of a plurality of synchronous frames each of which has synchronous data and coding data. Data items in the coding data contributed to creation of the same column of the error correction code are arranged at regular intervals of E in the recording data string. A data segment length L is obtained by adding an additional synchronous frame to the recording data string. Wherein, a physical segment length A satisfies the equation L=mA, m is a natural number. And A is set indivisible by E.

Optical disk medium and optical disk recording and reproducing apparatus

An optical disk apparatus has a first optical system having an objective lens with a first NA, a second optical system having an objective lens with a second NA lower than the first NA, an addition mechanism for adding focus error signals detected by the first and second optical systems, and an alignment mechanism for aligning the objective lens in accordance with the addition result of the addition mechanism.

Optical disk apparatus and optical disk processing method

An information recording medium according to an embodiment of this invention has a plurality of disk-like information recording layers, which are adhered to each other within an allowable decentering error range, and an embossed lead-in area assured on each information recording layer has first guard tracks which are formed within the range of the first radial distance from the radial position of the innermost periphery of the embossed lead-in area toward the outer periphery side, and second guard tracks which are formed within the range of the second radial distance from the radial position of the outermost periphery of the embossed lead-in area toward the inner periphery side.

Information recording medium, information reproduction apparatus, and information reproduction method

An information recording medium according to an embodiment of this invention has a plurality of disk-like information recording layers, which are adhered to each other within an allowable decentering error range, and a data area assured on each information recording layer, and has guard tracks within the range of a predetermined radial distance from the radial position of the innermost periphery of the data area toward the outer periphery.

Information recording medium, information reproduction apparatus, and information recording apparatus

An optical disk apparatus has a first optical system having an objective lens with a first NA, a second optical system having an objective lens with a second NA lower than the first NA. The optical disk apparatus at the time of processing the optical disk, when the optical system suitable recording/reproduction process of the optical disk is the second optical system, via the first optical system detecting a surface run-out of the optical disk and execute the focus lead-in process of the second optical system on the basis of a surface run-out detected; and when at the time of processing the optical disk, when the optical system suitable recording/reproduction process of the optical disk is the first optical system, processing the optical disk with the first optical system without detecting the surface run-out of the optical disk.

Growing community of inventors

Yokohama, Japan

Hideaki Ohsawa