Sanyo Electric Co., Ltd.

Sanyo Optec Design Co., Ltd.

Tokyo Optec Design Co., Ltd.

Kenji Nagatomi

Seiji Kajiyama

Katsutoshi Hibino

Seiichiro Takahashi

Yoichi Tsuchiya

Morio Nakatani

Yoshiyuki Matsumura

Shigeharu Shirane

Masayuki Yoshie

Shinsei Kasahara

Masayuki Hata

Yasuhiko Nomura

Yasuyuki Bessho

Masayuki Shono

Yasuyuki Kano

Kazushi Mori

Naoyuki Takagi

Noboru Mamiya

Kenji Asano

Tetsuhisa Hosokawa

Satoshi Kanai

Shogo Suzuki

An optical pickup device imparts different astigmatisms from each other to light fluxes in four light flux areas A through D formed around an optical axis of laser light, out of the laser light reflected on a disc. The optical pickup device also changes the propagating directions of the light fluxes in the light flux areas A through D to separate the light fluxes in the light flux areas A through D from each other. A signal light area where only signal light exists is defined on a detection surface of a photodetector. Sensing portions are arranged at a position corresponding to the signal light area. Accordingly, only the signal light is received by the sensing portions, thereby suppressing deterioration of a detection signal resulting from stray light.

Optical pickup device and optical disc device

An optical pickup device is so configured as to change the propagating directions of light fluxes in four light flux areas defined in the periphery of an optical axis of laser light, out of the laser light reflected on a disc, to separate the four light fluxes one from the other. A signal light area where only signal light exists is defined on a detecting surface of a photodetector. Sensors for signal light is disposed at a position in the signal light area to be irradiated by the signal light, and a tracking error signal is generated based on a signal from the sensors. A direct-current component of the tracking error signal resulting from positional displacements of the sensors is cancelled by adjusting a gain of the signal from the sensor.

An optical pickup device includes an astigmatism element which imparts astigmatism to laser light reflected on a disc, a spectral element which changes propagating directions of four light fluxes obtained by dividing a light flux of the laser light reflected on the disc to disperse the four light fluxes from each other, and a photodetector having a sensor group which receives the four light fluxes. The optical pickup device is further provided with a memory which holds a correction value for suppressing a DC component in a tracking error signal resulting from a positional displacement of the spectral element. The tracking error signal is corrected by the correction value to thereby suppress the DC component.

Optical pickup device, optical disc device and focus adjusting method

An optical pickup device has an astigmatism element which imparts astigmatism to reflected light of laser light reflected on a recording layer, and a spectral element into which the reflected light is entered, and which separates the reflected light. The spectral element is divided into four third areas by a first area having a certain width and formed along a straight line in parallel to a first direction, and by a second area having a certain width and formed along a straight line in parallel to a second direction. The spectral element is configured to guide the reflected light passing through the four third areas to respective corresponding sensors on a photodetector while making propagating directions of the reflected light different from each other, and to avoid guiding the reflected light entered into the first area and into the second area to the sensors.

Optical pickup device

An optical pickup device includes an objective lens portion which converges laser light at a first focal point and a second focal point; an actuator which positions the first focal point or the second focal point on a recording layer in a disc; an astigmatism element which sets a first focal line position and a second focal line position of the laser light reflected on the disc away from each other in a propagating direction of the laser light; a spectral element which disperses four light fluxes obtained by dividing the laser light reflected on the disc in four from each other; and a photodetector having a sensor group which receives the four light fluxes dispersed by the spectral element.

An optical pickup device has an astigmatism element which imparts astigmatism to reflected light of laser light reflected on a recording layer, and a spectral element into which the reflected light is entered, and which separates the reflected light. The spectral element is divided into six second areas by a straight line in parallel to a first direction, a straight line in parallel to a second direction, and a first area having a predetermined width and formed along a straight line in parallel to a third direction inclined from the first direction by 45 degrees. The spectral element is configured to guide the reflected light passing through the six second areas to corresponding sensors on a photodetector while making propagating directions of the reflected light different from each other, and to avoid guiding the reflected light entered into the first area to the sensors.

A spectral element separates first laser light in such a manner that an area including only signal light as reflected first laser light is formed on a photodetector. The photodetector is provided with a first sensor group which is disposed at an irradiation position of signal light of the separated first laser light, and a second sensor group which receives zero-th order diffraction light of a main beam and two sub beams of second laser light that has been transmitted through the spectral element. The second sensor group includes a four-divided sensor which receives the main beam. The four-divided sensor is disposed in an area surrounded by the first sensor group. Zero-th order diffraction light of the first laser light that has been transmitted through the spectral element is irradiated onto the four-divided sensor.

An optical system of an optical pickup device includes an astigmatism element which imparts astigmatism to BD light reflected on BD and CD light reflected on CD, and a spectral element which disperses four light fluxes of BD light and four light fluxes of CD light by diffraction, the four light fluxes of BD light and the four light fluxes of CD light being obtained by dividing the BD light reflected on the BD and the CD light reflected on the CD by a first straight line parallel to a converging direction by the astigmatism element, and a second straight line perpendicular to the first straight line. A photodetector of the optical pickup device is provided with first and second sensor groups for respectively receiving the four light fluxes of BD light and the four light fluxes of CD light dispersed by the spectral element.

A recording medium includes at least one recording layer on which information is recorded by multi-photon absorption, and a servo layer disposed in a laminated direction with respect to the recording layer and having a track for guiding a beam spot of laser light having a first wavelength and a beam spot of laser light having a second wavelength along a scanning trajectory. The servo layer and the at least one recording layer constitute a set of layers, and a plurality of sets of layers is formed in the laminated direction. The servo layer is made of a material having a high reflectance with respect to laser light having a third wavelength for generating a servo signal, and low reflectances with respect to the laser light having the first wavelength and the laser light having the second wavelength.

Recording medium, optical device, and recording and reproducing apparatus

An optical pickup device is provided with a spectral element which imparts diffraction in such a manner that four light fluxes of the first laser light are separated from each other, when a light flux of the first laser light and a light flux of the second laser light reflected on a recording medium having laminated recording layers and servo layers are divided into four by a first straight line in parallel to a converging direction by an astigmatism element, and a second straight line perpendicular to the first straight line, and that the four light fluxes of the first laser light propagate on an outer side than the light flux of the second laser light; and a photodetector including a first sensor group which receives the first laser light, and a second sensor group which receives the second laser light.

Two light flux areas are disposed in a direction along which a pair of vertically opposite angles defined by first and second straight lines are aligned, and the other two light flux areas are disposed in a direction along which the other pair of vertically opposite angles are aligned. A spectral element sets propagating directions of divided elements of each of light fluxes obtained by dividing each of the light fluxes by a third straight line intersecting with the first and second straight lines by an angle of 45 degrees, or by a fourth straight line orthogonal to the third straight line to disperse the divided elements on a photodetector. The photodetector is provided with sensors which individually receive the divided elements of the light fluxes.

An astigmatism element converges laser light in first and second directions to generate focal lines. A spectral element makes propagating directions of light fluxes entered into first through fourth areas different from each other to disperse the four light fluxes from each other. The direction along which the first and second areas are aligned is in parallel to a direction of a track image of a recording medium projected onto the spectral element. Each of the first and second areas has a surface area larger than a surface area of each of the third and fourth areas, and a boundary portion between the first and second areas, and the third and fourth areas includes a straight portion extending in a direction perpendicular to the direction of the track image.

An optical pickup device includes: a first light source for emitting recording laser light; a second light source for emitting reproducing laser light having a wavelength different from a wavelength of the recording laser light; an objective lens for converging the recording laser light and the reproducing laser light. A quarter wavelength plate is disposed between the first light source and the second light source, and the objective lens. A wavelength-selective polarized beam splitter is disposed between the quarter wavelength plate, and the first light source and the second light source. The reproducing laser light alone out of the recording laser light and the reproducing laser light reflected on recording medium is guided to a photodetector.

Optical pickup device and recording/reproduction device

A recording medium includes: at least one recording layer on which information is recorded by multi-photon absorption; and a servo layer disposed in a laminated direction with respect to the recording layer and having a track for guiding a beam spot of laser light having a first wavelength and a beam spot of laser light having a second wavelength along a scanning trajectory, wherein the servo layer and the at least one recording layer constitute a set of layers, and a plurality of sets of layers is formed in the laminated direction.

Recording medium, and recording and reproducing apparatus

An optical pickup device imparts different astigmatisms from each other to light fluxes in four light flux areas formed around an optical axis of laser light, out of the laser light reflected on a disc. The optical pickup device also changes the propagating directions of the light fluxes in the light flux areas to separate the light fluxes in the light flux areas each other. A signal light area where only signal light exists is defined on a detection surface of a photodetector. Eight sensing portions are arranged at a position corresponding to the signal light area. According to this arrangement, only the signal light is received by the sensing portions to thereby suppress deterioration of a detection signal resulting from stray light. Further, a push-pull signal, whose DC component is suppressed, is obtained by computing an output from the eight sensing portions by a predetermined formula.

Growing community of inventors

Kaizu, Japan

Kenji Nagatomi