Panasonic Corporation

Matsushita Electric Industrial Co., Ltd.

Naoto Shimada

Naoki Nakanishi

Hiroaki Yamamoto

Masahiko Nishimoto

Takuya Okuda

Shinichi Hamaguchi

Tatsuya Nakamori

Yuzo Shimizu

Daisuke Furukawa

Toshihiro Kuroda

Toyonori Kusuhara

The optical pickup device according to the present invention includes: a light source which emits a first light at a first wavelength, a second light at a second wavelength and a third light at a third wavelength; an optical path combining unit which combines vectors of the first, second and third light emitted by the light source, and matches optical axes of the first light and the third light; a light collection unit which condenses the light from the optical path combining unit into the optical information storage medium; a diffraction element which diffracts reflected light from the optical information storage medium; a first photo detector, a second photo detector and a third photo detector which receives the diffracted light from the first diffraction element; and a prevention unit formed between the first diffraction element and the first photo detector, the second photo detector and the third photo detector, and which prevents irradiation of + first-order diffracted light diffracted by the first diffraction element into the first photo detector, the second photo detector, and the third photo detector.

Optical pickup device

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.

The optical pickup device according to the present invention includes: a light source which emits light at first, second and third wavelengths; an optical path combining unit which combines vectors of the light at the first, second and third wavelengths which is emitted by the light source, and matches optical axes of the light at the first wavelength and the light at the third wavelength; a light condensing unit which condenses the light from the optical path combining unit onto the optical information storage medium; a diffraction element which diffracts light at the first, second and third wavelength which is reflected from the optical information storage medium, in a first direction and a second direction respectively; a first photo detector which receives light at the first, second and third wavelength that is diffracted in the first direction by the diffraction element; a second photo detector which receives light at the first and third wavelength that is diffracted in the second direction by the diffraction element; and a third photo detector which receives light at the second wavelength that is diffracted in the second direction by the diffraction element.

Optical pickup device having a structure providing efficient light usage

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 path coupling member aligns an optical axis directed to a light condensing member of the first wavelength light having a shortest wavelength with that of the third wavelength light having a longest wavelength. A diffraction element condenses +2nd order diffracted light of the first wavelength light and +1st order diffracted light of the second wavelength light and third wavelength light into a first photodetector, the &#x2212;2nd order diffracted light of the first wavelength light and &#x2212;1st order diffracted light of the third wavelength light into a second photodetector, and &#x2212;1st order diffracted light of the remaining second wavelength light into a photodetector, using &#xb1;2nd order diffracted light of the first wavelength light and &#xb1;1st order diffracted light of the second wavelength light and third wavelength light as signal light from an optical information recording medium. Consequently, the overall size of the optical pickup apparatus is reduced.

Growing community of inventors

Hyogo, Japan

Naoto Shimada