Panasonic Corporation

Matsushita Electric Industrial Co., Ltd.

Nalux Co., Ltd.

Takuya Okuda

Masahiko Nishimoto

Hiroaki Yamamoto

Naoki Nakanishi

Naoto Shimada

Kazutoshi Onozawa

Kazuhiko Yamanaka

Shinichi Ijima

Masayuki Ono

Yasuyuki Kochi

Tomoaki Tojo

Junichi Kubo

An optical pickup device includes a diffraction gratingfor separating a light beam emitted from a semiconductor laser element into at least three light beams. The diffraction gratingis divided into three regions by a straight line extending in a direction parallel to a tangent line of a track of an optical information recording medium. A second regionB is divided into a first sub-blockand a second sub-blockby a straight line extending in a direction parallel to a radius direction of the optical information recording medium. The first sub-blockhas a phase difference of approximately 180 degrees from the second sub-block. The first regionA has a phase difference of approximately 90 degrees from the first sub-blockand has a phase difference of approximately 180 degrees from the third regionC.

Optical pickup device

An optical pickup device includes a diffraction gratingfor separating an emitted light beam into at least three light beams. The diffraction gratingis divided into three regions by dividing lines Dand Dextending in a first direction parallel to a tangent line of a track of an optical information recording medium. A second regionB is divided into four sub-blocks by a dividing line Dextending in the first direction and a dividing line Dextending in a second direction that crosses the first direction. The sub-blocks located diagonally opposite to each other have a same phase, and the sub-blocks located adjacent to each other have a phase difference of approximately 180 degrees. The first regionA has a phase difference of approximately 90 degrees from each sub-block of the second regionB, and the first regionA has a phase difference of approximately 180 degrees from the third regionC.

A pickup device includes a diffraction gratingfor separating a light beam emitted from the light source into at least three light beams. The diffraction gratingis divided into four regions by straight lines extending in a direction parallel to a tangential direction of tracks of an optical information recording medium. A periodic structure of a second regionB has a phase difference of approximately 180 degrees from a periodic structure of a third regionC, and a periodic structure of a first regionA has a phase difference of approximately 180 degrees from a periodic structure of a fourth regionD.

An optical pickup device in which a hologram element has a plurality of different diffraction directions. In the tracking standard state, the hologram element is divided into six areas by a straight line connecting two strength center points of two light beams, and by two straight lines that are perpendicular to the straight line. By adding the amount of light received by an area demarcated by two straight lines that pass the two strength center points, to the amount of light received by one of two outer areas sandwiching the area depending on the type of the light beam, it is possible to obtain a well-balanced tracking error signal for each of the two light beams.

Optical pickup for recording and reproducing information with a plurality of types of optical information recording mediums

An optical head includes a fixed part, a movable part movably held by a plurality of wires fixed on the fixed part, and magnets fixed to the fixed part. The movable part includes a movable-part housing, a heatsink held by the movable-part housing, a light emitting element and a light receiving element both mounted on the heatsink, magnets provided to both sides of the movable-part housing to contact the heatsink, an objective lens held by the movable-part housing to allow an emitted laser beam from the light emitting element to focus, and a diffraction grating provided between the objective lens and the light emitting element and between the objective lens and the light receiving element. The gap between each coil and the adjacent magnet is filled with ferrofluid having a higher thermal conductivity than the atmosphere.

Optical head

An optical pickup having a light-emitting element, an objective lens unit, a reflecting mirror and a light-receiving element, emits a beam onto an optical recording medium and uses a reflected beam to read recorded information. In the objective lens unit, a central part of a surface, facing the light-emitting element, of an objective lens disposed so that an optical axis is substantially aligned with a chief ray of the beam emitted by the light-emitting element, is a transmissive diffraction grating, and a central part of a surface of the objective lens that will face the optical recording medium is a convex mirror which bulges toward the light-emitting element. The reflecting mirror, which is annular and encompasses the optical axis of the objective lens, reflects toward the objective lens the beam from the light-emitting element that has passed through the transmissive diffraction grating and been reflected by the convex mirror. The light-receiving element receives first-order diffracted light, of the reflected beam from the recording medium, diffracted by the transmissive diffraction grating.

Growing community of inventors

Kyoto, Japan

Takuya Okuda