Sanyo Electric Co., Ltd.

Katsutoshi Hibino

Kenji Nagatomi

Yasuko Teragaki

Yoichi Tsuchiya

Seiji Kajiyama

Kazushi Mori

Naoyuki Takagi

Youichiro Goto

Shuichi Ichiura

Noboru Mamiya

Yasuyuki Kanou

Kenji Torazawa

Kenji Asano

Koichi Tada

Seiichiro Takahashi

Masahiro Higuchi

Takanari Kusafuka

Tateo Toyama

Shigeki Hori

Michiaki Sato

Shogo Suzuki

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.

Optical pickup device and optical disc device

An optical pickup device includes an astigmatism element which sets focal line positions to be defined by convergence of laser light away from each other, a diffraction element which diffracts four light fluxes obtained by a light flux of the laser light to disperse the four light fluxes from each other, and a photodetector having a first sensing section and a second sensing section which respectively receive m-th order diffraction light and n-th order diffraction light of the four light fluxes. In this arrangement, the first sensing section receives eight light fluxes obtained by dividing the four light fluxes of the m-th order diffraction light by two straight lines to output detection signals of the number less than eight.

An optical pickup device radiates laser light to a disc having a plurality of recording layers in a direction of lamination. The optical pickup device includes an astigmatic element and a spectral element. The astigmatic element allows reflected light from the disc to converge in a first direction and form a first focal line at a first position, and allows reflected light to converge in a second direction and form a second focal line at a second position closer to the disc than the first position. The spectral element splits a reflected light flux in two along a straight line parallel to the first direction and turns traveling directions of the split two light fluxes into directions separated from each other. Here, the spectral element is interposed between the second focal line of the reflected light from a target recording layer and the second focal line of the reflected light from a deeper recording layer than the target recording layer. The photodetector is interposed between the first and second focal lines of the reflected light from the target recording layer.

Optical pickup device

An optical pickup apparatus is provided with an angle adjusting element. The angle adjusting element changes a propagation direction of luminous fluxes of four luminous flux regions set about an optical axis of the laser light, out of laser light reflected by a disc, and mutually disperses the luminous fluxes. A signal light region in which signal light only is present appears on a detecting surface of a photodetector. A sensor pattern for signal light is placed at a position irradiated with the signal light within this region. A sensor pattern for a spherical aberration detection is placed on an inner side of this region.

Optical pickup apparatus, focal-point adjusting method, and optical disc apparatus

An optical pickup apparatus is provided with an angle adjusting element. The angle adjusting element changes a propagation direction of luminous fluxes of four luminous flux regions set about an optical axis of the laser light, out of laser light reflected by a disc, and mutually disperses the luminous fluxes. A signal light region in which signal light only is present appears on a detecting surface of a photodetector. A sensor pattern for signal light is placed at a position irradiated with the signal light within this region. A sensor pattern for a coma aberration detection is placed on an inner side of this region.

An optical pickup apparatus includes an astigmatic element, an angle adjusting element for contradicting propagation directions of luminous fluxes within four different luminous flux regions out of a reflected light, a polarization adjusting element. Two of the luminous flux regions are placed in a direction in which aligned are a set of opposite angles made by the two mutually crossing straight lines respectively parallel to a first convergence direction and a second convergence direction vertical to the first convergence direction by the astigmatic element, and the remaining two luminous flux regions are placed in a direction in which an alternate set of opposite angles are aligned. The polarization adjusting element differentiates polarization directions of luminous fluxes which are selected out of the luminous fluxes within the four luminous flux regions and which are adjacent in a peripheral direction in which the optical axis of reflected light serves as an axis.

Optical pickup apparatus and focal-point adjusting method

An optical element is disposed on an optical path between a beam branching element and a photodetector. The optical element is disposed at a focal position of a stray light beam reflected by a recording layer except a target recording layer, and shields or attenuates the light beam in a region where the stray light beam converges.

Optical pick-up capable of eliminating stray beams

A diffraction element is disposed between a beam branching element (such as a beam splitter) and a photodetector. The diffraction element further segment an interference fringe introduced into stray light by a diffraction grating which divides a laser beam emitted from a laser beam source into a main beam and two sub-beams.

A backlight apparatus has a light guide plate with a side surface through which the light from a light source enters The light source extends longitudinally in a specific direction. The light guide plate has a light emitting surface and a back surface opposed to the emitting surface. Horizontal grooves are formed on the back surface parallel to the longitudinal direction of the light source. A width of a flat portion defined between the grooves decreases as goes away form the light source.

Backlight apparatus and light guide plate

An optical pickup apparatus including a polarization plane rotary unit arranged between a semiconductor laser and an objective lens, and a polarizing film arranged between the polarization plane rotary unit and the objective lens. The polarization plane rotary unit includes liquid crystal, two glass plates sandwiching the liquid crystal, and transparent electrodes patterned to a predetermined configuration on an inner face of these glass planes. The polarization plane rotary unit permits passage of the laser beam without rotating the plane of polarization of the entire laser beam at the time of recording, and permits passage of the laser beam with the plane of polarization of the center portion of the laser beam rotated and the plane of polarization of the remaining outer portion of the laser beam not rotated at the time of reproduction. Only the outer portion of the laser beam is focused on a magneto-optical disk in a reproduction mode, so that a main beam of a small spot is formed by mutual interference. Since the plane of polarization of the laser beam directed on the magneto-optical disk is not rotated, the Kerr angle of rotation can be detected at high accuracy. As a result, the reproducibility is improved.

Superresolution optical pickup apparatus

A light guide plate is provided including a first lens portion comprising a plurality of recessed or projected lenticular unit lenses formed of the same resin as that of the light guide plate on a light emission surface. The plurality of lenticular unit lenses in the first lens portion are triangular prism portions whose respective vertexes have an angle of 125.degree. to 165.degree. and are so arranged that their respective ridge lines are nearly parallel to each other. Such construction makes it possible to set the number of lenticular lens sheets used to one or to further eliminate the necessity of the lenticular lens sheets, so that the cost of parts and the fabrication cost of the light guide plate can be reduced. A second lens portion may be provided on a light reflective surface opposite to the light emission surface on which the first lens portion is disposed, the second lens portion including a plurality of recessed or projected lenticular unit lenses formed of the same resin as that of the light guide plate. Alternatively, a light guide plate is provided having a plurality of grooves with approximately equal groove widths formed on a surface opposite to a light emission surface, the grooves being arranged substantially parallel to each other and the spacing between the grooves narrowing as the distance from the light incident surface increases, with the spacing from the far end of one of the plurality of grooves proximate to the light incident surface to the near end of a groove adjacent thereto farther away from the light incident surface being 5 to 15 times the groove width.

Light guide plate and surface light source using the light guide plate

An optical disc readout apparatus is disclosured. The apparatus adjusts an optical system which leads the laser beam output from the laser diode to the objective according to the board thickness of the optical disc, and focuses the laser beam onto the information-bearing surface of the disc by the collaboration of the adjusted optical system with the objective. The adjustment can be achieved by, for example, advancing the correction lens to the optical path of the optical system or retreating the correction lens from such optical path. An another apparatus is disclosured. The another apparatus is provided with a first optical system which leads the laser beam output from the first laser diode to the common optical system and a second optical system which leads the laser beam output from the second laser diode to the common optical system. Either the first optical system or the second optical system includes a correction lens. One of the systems is selected according to a type of the loaded disc. Both the first optical system and the second optical system can focus the laser beam onto the information-bearing surface of the disc.

Optical disk readout apparatus

An optical pick-up comprising a laser source (laser diode), a plurality of optical elements, beam splitter, focusing means (microlens) and detecting means (photo diode) is disclosed. The plurality of optical elements focuses a laser beam which is emitted from the laser diode onto a magneto-optic disc, and focuses a laser beam which is reflected from the magneto-optic disc onto a photo detector. The beam splitter splits the laser beam, which is emitted from the laser diode, by reflecting a part of the laser beam at a first surface and by refracting the other part of the laser beam at the first surface. The reflected part is entered into the optical elements and the refracted part is passed through the beam splitter and then emerged from a second surface. The microlens is integrally formed on the second surface of the beam splitter by the ion exchanging method. And the microlens focuses the beam which is emerged from the second surface. The photo diode detects the beam which is focused by the microlens. The beam splitter, the beam splitter, the microlens and the photo diode are mounted on a common substrate.

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Kaizu, Japan

Katsutoshi Hibino