Kabushiki Kaisha Toshiba

Tokyo Shibaura Denki Kabushiki Kaisha

Isao Hoshino

Masahiko Tanaka

Hisashi Yamada

Yoshinori Honguh

Teruo Murakami

Akihiro Kasahara

Toyoki Taguchi

Takayuki Asano

Shoko Wachi

Toshihiro Sugaya

Kazushige Mori

Takashi Yoshizawa

Hiromichi Kobori

Akino Inoue

Hiroharu Satoh

Masaaki Matsumaru

Mineharu Uchiyama

Kei Shimura

Sadanari Fujimoto

Yoshiharu Imaoka

An optical head comprising two light sources, a beam splitter, and two photodetectors. The first light source emits a first light beam to be applied to the recording surface of a first-type optical disk. The second light source emits a second light beam to be applied to the recording surface of a second-type optical disk. The first light beam and the second light beam intersect with each other at an angle other than 90.degree.. The beam splitter is provided at the intersection of the first and second light beams. The beam splitter guides both light beams in a common optical path which extends to the recording surface of either optical disk. The beam splitter guides the first light beam reflected from the first-type optical disk toward the first light source, and the second light beam reflected from the second-type optical disk toward the second light source. The first photodetector detests the first beam reflected from the first-type optical disk. The second photodetector detests the second beam reflected from the second-type optical disk.

Optical head, optical component for use therein, method of manufacturing

An optical head device adapted to be optically coupled to an optical disk includes a light-source laser and an objective lens optically coupled thereto. This lens receives an output light of the light source, and causes it to be projected onto the optical disk to form a focused spot thereon. Photodetectors are optically coupled to the lens in one optical path so that they are responsive to a light component which is reflected from the optical disk toward the photodetectors by way of the objective lens. A beam-shaping prism is located between the lens and a group of the light source and the photodetectors in the optical path. When the laser output light travels toward the lens, the prism reshapes the light into a predetermined isotropic beam profile. When the reflected light from the optical disk propagates reversely along the same optical path to enter the beam-shaping prism, this prism permits such an incident light to pass through itself toward the photodetectors.

Light beam shaping device to change an anisotropic beam to an isotropic

An optical head apparatus includes a stationary optical system having a light source and a detector for detecting light reflected by a recording medium, which stationary optical system is arranged at a position fixed to the recording medium. Plural objective lenses for focusing/irradiating light emitted from the light source onto the recording medium are arranged on a rotating blade which is provided to be rotatable in a direction parallel to the recording medium. By controlling the waveform of a current to be supplied to a tracking coil, the blade is rotated and a desired one of the objective lenses is located on an optical axis of the light irradiated onto the recording medium.

Recording/reproducing optical head apparatus compatible with different

A primary optical disk recording apparatus comprises a first light source for recording a signal on a primary optical disk, an objective lens for converging a light beam from the first light source on the primary optical disk, a second light source for detecting a focus error between the objective lens and the primary optical disk, and a controller for detecting a reflection light beam from the first light source, which is reflected from the primary optical disk, while the signal is being recorded on the primary optical disk, and for subjecting a signal of the reflection beam to an arithmetic operation process, thereby detecting a first focus error signal and controlling the focus error on the basis of the first focus error signal.

Apparatus for recording information on a primary optical disk to

Optical head used for recording on optical recording medium having

An optical head device adapted to be optically coupled to an optical disk includes a light-source laser and an objective lens optically coupled thereto. This lens receives an output light of the light source, and causes it to be projected onto the optical disk to form a focused spot thereon. Photodetectors which are arranged near the light-source laser are optically coupled to the lens in one optical path so that they are responsive to a light component which is reflected from the optical disk toward the photodetectors by way of the objective lens. A beam-shaping prism is located between the lens and a group of the light source and the photodetectors in the optical path. When the laser output light travels toward the lens, the prism reshapes the light into a predetermined isotropic beam profile. When the reflected light from the optical disk propagates reversely along the same optical path to enter the beam-shaping prism, this prism permits such an incident light to pass through itself toward the photodetectors.

An optical disk apparatus includes a semiconductor laser for emitting a light beam, and an automatic power control or APC circuit for driving the laser. A compound prism structure is optically coupled to the laser in an optical head section, and defines a first optical path for causing a front laser light to be projected onto a rotating optical disk and guiding a reflected light therefrom toward a first photodetector, and a second optical path for guiding a part of the reflected light toward a second photodetector. An output signal of the first photodetector is used to generate a reproduced information signal. An output signal of the second photodetector is fed back to the APC circuit as a front light monitor signal. A part of a laser control signal internally generated in the APC circuit is supplied through a wiring line to a noise reduction circuit as a laser noise monitor signal. The noise reduction circuit subtracts this noise monitor signal from the reproduced information signal to provide a noise-suppressed information signal.

Noise reduction system for optical record and reproduction apparatus

In an information recording/reproducing apparatus, a light beam emitted from a semiconductor laser is guided to a beam splitter. The light beam passing through an incident surface of the splitter is splitted into first and second light beam by a beam splitting layer. The first beam passing through the splitting layer is emerged from a first emerging surface and guided to an optical disk. The first light beam after being reflected from the optical disk is returned to the first emerging surface and passes through the first emerging surface. The returned first light beam passed through a second emerging surface and defected by a detector so that a retrieving signal is generated from a detector. The second light beam reflected from the beam splitting layer is directed to a concave mirror of the splitter and is converged on a mirror detector through a third emerging surface so that a mirror signal for controlling the semiconductor laser is detected.

Apparatus for optically recording and reproducing information from an

In an optical head, a converging lens and a holographic optical element are arranged in the optical path of light reflected by the recording surface of an optical memory recording medium and passing through an objective lens. The holographic optical element has a hologram formed in at least one of two regions split by a region splitting line crossing the optical axis of the converging lens. A photodetector is arranged on the extension line of the optical axis. The photodetector has a plurality of detection surfaces which are respectively split along the region partition line of the holographic optical element to detect light beams diffracted by the hologram. The optical head also includes a detecting system for detecting a focusing error of the objective lens of the optical head by performing predetermined arithmetic operations using an incorporated processing circuit on the basis of output signals obtained by the plurality of detection surfaces of the photodetector.

Optical head including focusing error detecting system

An optical head which can be rotated about the rotation center by a magnetic force. There is a photodetector which is divided into a plurality of detection regions and as the optical head rotates, different detection regions are examined to determine a tracking error. Rotating between the inner and outer peripheral portions of an optical disk, the optical head selects a track on the optical disk on which information is recorded, radiates a light beam focused on the selected track, receives the light beam reflected by the optical disk to a second photodetector having three divided parallel sensor segments, and reproduces the information recorded on the optical disk. In consideration of the fact that in an optical disk rotated at a constant angular velocity, the degree of modulation of a retrieving information signal recorded on a recording layer on the optical disk is increased toward the outer peripheral portion, the sensor segments of the photodetector are arranged such that the projection of a track on the inner peripheral portion in an information recording area, of track projections which move on the sensor segments, does not cross the three divided sensor segments upon rotation of the optical head.

Rotary-type optical head

In an apparatus for detecting a focusing error of an objective lens, a light beam reflected from an optical disk passes the objective lens and is reflected from a beam splitter. The reflected light beam is incident on a cylindrical lens so that the light beam is converged in one direction by the cylindrical lens. The converged light beam is incident on first and second triangular prisms so that it is divided into two beams and the two beams are guided into different directions and form beam spots on photo-detectors, respectively. In the respective triangular prism, light rays of the light beam pass through different optical paths. Thus, an aberration is applied to the light beam from the prisms. Accordingly, the shape of each beam spot on the photo-detector is changed in accordance with a focusing error.

Focusing error detecting apparatus

In a data recording/reproducing apparatus, a DC motor is provided for rotating an optical disk. A recording/reproducing head is driven to move over the disk linearly in the radial direction of the disk, thereby defining a plurality of data-storing tracks on the disk. A motor control section is provided for controlling the rotation of the disk so as to change the angular velocity of the disk when the head tracing is changed among the track groups. While the head is tracing the tracks included in the same track group, the rotation of the disk is made constant so that the disk rotates at a constant angular speed.

Information recording/reproducing apparatus with disk having sections of

An optical-disk system is disclosed which comprises an optical-disk rotating in accordance with constant linear velocity technique, a signal input device for producing an information signal digitally encoded, and address generator for generating an address signal, an interleave circuit for commonly leaving both the information signal and the address signal, and a write controller for modulating a write beam incident to the optical-disk in response to the output signal from the interleave circuit and for forming at least one sector including both the commonly interleaved signals on the optical-disk.

Growing community of inventors

Yokohama, Japan

Isao Hoshino