Ricoh Company, Ltd.

Masaaki Sofue

Tatsuaki Sakurai

Hideo Inuzuka

Takashi Ogawa

Junichi Watanabe

Tetsuo Kanno

Syuichi Honda

Yoshiaki Aota

Toshimichi Hagiya

Makoto Yamahata

Ryuuji Kudou

Ryuji Kudo

Ryuuji Kudoh

The present invention provides a large scale integrated circuit (LSI) for calculating servo signals (e.g., a focusing signal, a tracking signal, etc.) from the output signals received from a plurality of photo detectors, as used within an optical disk apparatus. The invention provides a switching circuit and a gain changing circuit coupled to the LSI such that a single LSI may be used for at least two different photo detector configurations as may be found in at least two different pick-up devices.

Signal operational circuit for a multi-beam pick-up device

An optical disk apparatus is described which can read information from and write information to optical disk of different thicknesses. The optical disk apparatus includes coupling lenses which alter the focusing capabilities of an objective lens which controls reading and writing to the optical disk. Thus, the present invention allows both 'standard density' and 'high density' optical disks to be accessed by the same optical disk apparatus.

Optical disk apparatus for accessing optical disks with different

In order to accurately detect a tracking error signal, the position of a sub-beam Bs1 with a lower shading rate is located at a position ahead of the position of a main beam Bm in the recording direction of an optical disk, and the position of a sub-beam Bs2 with a higher shading rate is located at a position behind the position of the main beam Bm in the recording direction of the optical disk. Therefore, the unequal amount of optical information created by the different shading rates is counterbalanced by the fact that the portions of the optical disk where the sub-beams Bs1 and Bs2 are directed have different reflective rates. Accordingly, the amount of optical information from each sub-beam received by the tracking error signal photo detector is made equal, and the tracking error signal can be accurately detected.

Optical pickup apparatus for accurate detection of a tracking error

A layer beam controller for an optical storage apparatus includes a laser beam generator, a laser beam power varier for varying the laser beam power to first, second, and third power levels, a memory for storing predetermined reference values including first reference values corresponding to the first power level and second reference values corresponding to the second power level, a light amount detector for detecting a light amount of the laser beam, a laser beam power corrector for correcting the laser beam power at the respective power level by comparing the light amount and a corresponding one of the predetermined reference values selected by a type of the compact disk in operation in the optical storage apparatus. The laser beam controller further includes a power level assigner for assigning the first, second and third power levels based on the type of disk.

Method and apparatus for changing laser beam power of an optical storage

An optical disk unit for recording or reproducing information contained on an optical disk, wherein the optical head is mounted on a base that slides freely along a seek shaft. There is a clearance in the structure where the head base holds the seek shaft that allows for sliding of the head base with respect to the seek shaft. Wobbling of the head base during movement along the seek shaft, caused by the clearance around the seek haft, is reduced by a pressing portion mounted on the head base which presses against the seek shaft.

Optical disk unit having reduced wobble

An optical disk presents unit an object lens from being affected by an external disturbance caused by a reversed moving direction of an optical head when information is recorded or reproduced to or from an optical disk. The last moving direction of an optical head which has arrived at a target position of an optical disk is detected and, if it is opposite to a moving direction of the optical head for recording or reproducing information, the moving direction is inverted to the recording/reproducing moving direction before the optical head starts recording or reproducing information. At the time when the optical head inverts the moving direction, recording or reproduction of the information is not started. Therefore, no vibration or shock is applied to an object lens at the beginning of a recording or reproducing operation which might cause errors.

Optical disk unit having reduced recording and reproducing errors

The present invention relates to an optical data recording/reproducing device wherein an optical system holding portion holding a movable optical system having a carriage and a seek unit, and an emitting/detecting system holding portion holding an emitting/detecting system having an optical pickup unit are formed on the same housing. A number of components are reduced, a strength of the holding portions is improved, and an optical axis of each of systems is regulated with referring to the same housing. Therefore, an accurate assembling can be realized.

Optical data recording/reproducing device

A disk cartridge driving apparatus contains a loading mechanism for loading a cartridge or cassette case inserted through an opening and a spindle motor, optical head, optical head driving mechanism for recording and reproducing data from a disk in the cartridge or cassette case. The spindle motor, optical head and optical head driving mechanism are flexibly sealed to prevent the entry of dust even when a disk cartridge is being loaded into the apparatus.

Disk cartridge driving apparatus

In an optical pickup device, signal light is reflected on an optical disk and is converged by a condenser lens. A polarizing plane of the signal light is rotated 45.degree. by a 1/2 wave plate. The signal light is then incident to a polarizing beam splitter at an incident angle .theta.. The polarizing beam splitter is constructed by a plane parallel plate having a polarizing coating film. An s-polarized component of light reflected on the polarizing beam splitter is received by first divisional light-receiving elements and a difference signal between outputs of the first divisional light-receiving elements is set to a tracking control signal. A p-polarized component of light transmitted through the polarizing beam splitter is received by second divisional light-receiving elements and a difference signal between outputs of the second divisional light-receiving elements is set to a focusing control signal. Sum signals of the first and second divisional light-receiving elements are respectively inputted to a reproducing signal detector. The reproducing signal detector obtains a reproducing signal of recorded information by calculating a difference between these sum signals.

Optical pickup device

An optical disk apparatus for an optical disk enclosed in a disk cartridge comprises a casing for accommodating the cartridge through a cassette insertion aperture formed therein. A disk drive motor for rotating the optical disk, a loading assembly for detachably loading the cartridge on the disk drive motor, and an optical pickup device for recording data on and/or reproducing data from the optical disk are provided in the casing. Deflecting member provided for sealing the periphery of the optical pickup device against the flow of outside air introduced in the casing. A specific air-seal or door structure is provided for preventing introduction of air from the cassette insertion aperture into the casing. In the case that the optical pickup device comprises an optical head casing and an optical system accommodated in the optical head casing, the optical head casing is provided with air-supply means for supplying pressurized air into the optical head casing to maintain the interior of the optical head casing at a pressure higher than the exterior thereof.

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Tokyo, Japan

Masaaki Sofue