Sony Corporation

Ricoh Industrial Solutions Inc.

Kamon Uemura

Akio Yamakawa

Kiyoshi Ohsato

Masamichi Utsumi

Naoya Eguchi

Takamichi Yamakoshi

Yasushi Tomita

Kenichi Ishizuka

An optical disk apparatus driving an optical disk includes a tilt-angle adjusting unit configured to adjust a tilt angle indicating the tilt of an optical axis of laser light emitted from a pickup to detect an optimal tilt angle at which a traverse signal has the maximum amplitude and a storing unit configured to store information about the optimal tilt angle. When the optical disk has multiple recording layers on one side, the tilt-angle adjusting unit adjusts the tilt angle with respect to each of the multiple recording layers to detect the optimal tilt angle and the storing unit stores information about the optimal tilt angle with respect to each of the multiple recording layers. The tilt angle with respect to each of the multiple recording layers is controlled in accordance with the information about the optimal tilt angle with respect to each of the multiple recording layers.

Optical disk apparatus, control method, and program

A laser diode applies a laser beam through a grating, a beam splitter, and an objective to a compact disc. A laser beam reflected by the compact disc is applied through the objective and the beam splitter to a photodiode. The objective has a large numerical aperture of 0.6 in order to be able of play back a digital video disc that has a thin substrate and contains information recorded at a high density. To prevent the photodiode from suffering aberrations caused due to the large numerical aperture of the objective, the photodiode has a relatively small photodetector unit having a normalized detector size ranging from 3 &mgr;m to 16 &mgr;m, for detecting only returning light up to a numerical aperture of 0.3 and not detecting light of greater numerical aperture values.

Apparatus and method for recording and reproducing information from a plurality of recording medium having different thicknesses and recording densities

An optical pickup including a light source for radiating a light beam, a diffraction element for separating a light beam radiated from the light source into at least three beams, namely a main beam and two side beams, an objective lens for converging the light beams separated by the diffraction element on a signal recording surface of the optical recording medium, a light receiving unit having a four-segment first light receiving portion for receiving the main beam reflected by the recording surface of the optical recording medium and second and third light receiving portions arranged on both sides of the first light receiving portion for receiving the side beams reflected by the recording surface of the optical recording medium, and a calculation unit for generating a first tracking signal based on respective outputs of the first light receiving portion and for generating a second tracking signal based on outputs of the second and third light receiving portions.

Optical pickup for discriminating between and reading different types of optical discs

A laser diode applies a laser beam through a grating, a beam splitter, and an objective to a compact disc. A laser beam reflected by the compact disc is applied through the objective and the beam splitter to a photodiode. The objective has a large numerical aperture of 0.6 in order to be able of play back a digital video disc that has a thin substrate and contains information recorded at a high density. To prevent the photodiode from suffering aberrations caused due to the large numerical aperture of the objective, the photodiode has a relatively small photodetector unit having a normalized detector size ranging from 3 .mu.m to 16 .mu.m, for detecting only returning light up to a numerical aperture of 0.3 and not detecting light of greater numerical aperture values.

Apparatus and method for recording and reproducing information from a

An objective lens having at least two regions of different numerical apertures is configured for focusing a light beam through the regions of the different numerical apertures on two different signal recording surfaces of at least two optical discs having light transmitting layers of different thicknesses. Since the objective lens is integrally formed by at least two lens portions, a light beam outgoing from a common light source is focused on signal recording surfaces of at least two optical discs having the light transmitting layers of different thicknesses.

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Tokyo, Japan

Kamon Uemura