Sanyo Electric Co., Ltd.

Yoichi Tsuchiya

Seiji Kajiyama

Shuichi Ichiura

Yasuyuki Kanou

Hitoshi Terasaki

Osamu Ota

Kenji Nagatomi

Masato Yamada

Seizo Kato

Yasuyuki Kano

Yoshimoto Yamaguchi

Toshio Ito

Koichi Tada

Masayuki Hata

Yasuhiko Nomura

Yasuyuki Bessho

Masayuki Shono

Toshio Harada

Katsutoshi Hibino

Masami Shimizu

Atsushi Yamaguchi

Kenji Tanase

Satoshi Sumi

Yoshihisa Suzuki

Yoshiaki Maeno

Seiichiro Takahashi

Masahiro Higuchi

Youichiro Goto

Shigeki Hori

Tateo Toyama

Mikio Ichihashi

Mitsuhiko Maeda

Kanichi Koyama

Masaaki Shidochi

Yasuyuki Matsushita

Hitotoshi Kimura

An optical pickup apparatus changes a propagation direction of luminous fluxes, out of a laser light reflected by a disc, in four luminous flux regions set about a laser optical axis so as to mutually disperse these luminous fluxes. A signal light region in which only a signal light is present appears on a detection surface of a photodetector. A plurality of sensors for a signal light are placed at positions irradiated with the signal light within the region. When an arithmetic process is performed on a detection signal outputted from each sensor, a DC component occurring in a tracking error signal is suppressed.

Optical pickup apparatus and optical disc apparatus

A monolithic red/infrared semiconductor laser device is joined to a blue-violet semiconductor laser device. The distance between a blue-violet emission point in the blue-violet semiconductor laser device and an infrared emission point in an infrared semiconductor laser device is significantly shorter than the distance between a red emission point in a red semiconductor laser device and the infrared emission point. A blue-violet laser beam, a red laser beam, and an infrared laser beam respectively emitted from the blue-violet emission point, the red emission point, and the infrared emission point are introduced into a photodetector after being incident on an optical disk by an optical system comprising a polarizing beam splitter, a collimator lens, a beam expander, a &#x3bb;/4 plate, an objective lens, a cylindrical lens, and an optical axis correction element.

Semiconductor laser apparatus, method of manufacturing semiconductor laser apparatus, and optical pickup apparatus

Provided is an optical pickup device capable of suppressing an increase in the number of parts and complication of an optical system while a diffraction grating is used as an optical axis correcting element. Three kinds of blue, red, and infrared laser light beams are emitted from laser element provided in the same CAN package. A blue light emitting point (wavelength: 405 nm) and an infrared light emitting point (wavelength: 780 nm) are arranged in a layer forming direction of the laser elements such that an interval (d) between the light emitting points becomes shorter than an interval (d) between each of the light emitting points and a red light emitting point. An optical axis of the laser light beam emitted from the red light emitting point (wavelength: 650 nm) is aligned with an optical axis of the laser light beam emitted from the blue or infrared light emitting point by using the diffraction grating. The number of diffraction gratings for optical axis correction can be made to one and a single photo detector can be commonly used for laser light beams having different wavelengths.

Optical pickup device

A blue-violet emission point, an infrared emission point, and a red emission point in a semiconductor laser apparatus are arranged so as to be arranged in this order on a substantially straight line along a first direction. A blue-violet laser beam emitted from the blue-violet emission point and a red laser beam emitted from the red emission point are incident on an optical disk by an optical system comprising a polarizing beam splitter, a collimator lens, a beam expander, a &#x3bb;/4 plate, an objective lens, a cylindrical lens, and an optical disk, is returned from the optical disk, and is introduced into an photodetector. The infrared laser beam emitted from the infrared emission point is incident on the optical disk by the optical system, is returned from the optical disk, and is introduced into the photodetector.

Semiconductor laser apparatus and optical pickup apparatus

In a beam irradiation device of the present invention, laser beams emitted from a semiconductor laser impinge on an irradiation lens supported by a lens actuator. The laser beams that have passed through the irradiation lens change in outgoing angle in the direction of a y-z plane as the lens actuator is driven. A laser beam scan in the target region is thus performed. A part of the laser beams that have passed through the irradiation lens is reflected and separated by a beam splitter. The separated beams are converged on a PSD through a converging lens. A DSP control circuit monitors a scan position of the laser beams that have passed through the irradiation lens based on a signal from the PSD. When an irradiation position has deviated from a scan trajectory, the DSP control circuit controls an actuator driving circuit to draw the irradiation position back onto the scan trajectory. This beam irradiation device can realize a smooth and stable beam scan operation with a simple construction.

Beam irradiation device

Provided are an optical pickup device, which is capable of detecting and correcting spherical aberration while suppressing an increase in the number of construction elements and without increasing outer dimensions of a pickup device main body, and a recording and/or reproducing device having the optical pickup device built therein. A lens is designed such that when the thickness of a disk protective layer is greater than an optimum value, returning light (reflection light) from a disk is condensed on a sensor. The sensor is arranged at a condensing point and has a shape with which around 50% of the returning light is received when the thickness of the protective layer assumes the optimum value. With this construction, the quantity of light received by the sensor is increased when the thickness of the protective layer is greater than the optimum value, and is conversely reduced when the thickness of the protective layer is smaller than the optimum value. As a result, it becomes possible to detect the direction and degree of a thickness error with reference to the magnitude of an output from the sensor and to correct spherical aberration based on a result of the detection.

Optical pickup device and recording and/or reproducing device

A magneto-optical disk apparatus includes a magnetic head in a position opposed to an objective lens included in an optical head with a magneto-optical record medium therebetween. The magneto-optical disk apparatus includes a magnet for cancelling a first magnetic field emitted toward the magnetic head from a magnet for focus servo-control or tracking servo-control of the objective lens. The magnet emits a second magnetic field in a direction toward the magnetic head. The second magnetic field is opposite in direction to the first magnetic field, and has the same intensity as the first magnetic field. Consequently, the signal can be accurately reproduced from the magneto-optical record medium while removing a magnetic influence from the magnet included in the optical head.

MAGNETO-OPTICAL DISK APPARATUS CAPABLE OF ACCURATE REPRODUCTION OF SIGNAL BY REMOVING MAGNETIC INFLUENCE BY MAGNET INCLUDED IN OPTICAL HEAD AND METHOD OF DETECTING INTENSITY OF MAGNETIC FIELD APPLIED BY MAGNET

An optical pickup device includes a semiconductor laser, a collimater lens, an optical member, a halfmirror, an objective lens, a collecting lens and a photodetector. The collimator lens collimates a laser beam from the semiconductor laser. The optical member diffracts the laser beam which has been collimated by the collimator lens outward along the direction of the shorter diameter of the laser beam, and emits a laser beam having a prescribed aspect ratio. The halfmirror passes the laser beam from optical member and reflects one half the light reflected from a signal recording surface of an optical disk to the photodetector. The objective lens focuses the laser beam on the signal recording surface. The collective lens collects the laser beam from the halfmirror. The photodetector detects the laser beam. Therefore, the optical pickup device is capable of converting the aspect ratio of the laser beam emitted from the semiconductor laser, and hence it becomes possible to irradiate the optical disk with the laser beam having sufficient power for recording a signal.

In an optical pickup device ( ) including a laser light source ( ) and an objective lens ( ), an optical device ( ) is provided that transmits a laser beam of 635 nm in wavelength emitted from a first semiconductor laser ( A) straightforwardly into the objective lens ( ) while maintaining its incident intensity, and that selectively diffracts a laser beam of 780 nm in wavelength emitted from a second semiconductor laser ( B) to a desired direction while maintaining its incident intensity and directs only the predetermined center portion of the laser beam into the objective lens ( ). The optical pickup device ( ) records or reproduces a signal onto or from a plurality of types of optical disks differing in substrate thickness while directing a laser beam of sufficient intensity onto a signal recording plane.

Optical pickup compatible with a plurality of types of optical disks having different thicknesses

An optical pickup device which includes a semiconductor laser selectively generating a laser beam with a wavelength of 635 nm, a laser beam with a wavelength of 780 nm, and an optical device having a central region in which a hologram is formed and a peripheral region in which a diffraction grating is formed. In particular, the optical device is arranged immediately below an objective lens, and the central region allows transmission of the laser beam with the wavelength of 635 nm without any diffraction but increases the diameter of the teaser beam to the wavelength of 780 nm by diffraction. On the other hand, peripheral region allows transmission of the laser beam with the wavelength of 635 nm without any diffraction, but substantially shields the laser beam with the wavelength of 780 nm by diffraction. Thus, each laser beam with the wavelength 635 nm is transmitted through objective lens and focused on a signal recording surface of a DVD. The periphery of the laser beam with the wavelength of 780 nm is significantly diffracted by peripheral region of optical device and only the central portion of the laser beam enters objective lens while increasing its diameter. Thus, the laser beam with the wavelength of 780 nm is focused on a signal recording surface of a CD-R or a CD-ROM. Therefore, the optical pickup device is capable of compatibly reproducing the DVD, CD-R and CD-ROM.

Optical head for two different disk thicknesses with a light beam diameter control device

An optical disk recording/reproduction apparatus includes a semiconductor laser, an objective lens provided opposite an optical disk, an optical system for supplying a laser beam from the semiconductor laser to the objective lens, an aperture for not intercepting the laser beam in reproducing from a digital video disk and intercepting an outermost portion of the laser beam in reproducing from a compact disk, and a tracking servo mechanism for moving the objective lens in a tracking direction orthogonal to the running direction of a track of the optical disk. The aperture has an oblong opening that is longer in the tracking direction than in the track running direction.

Optical disk recording/reproduction apparatus for recording/reproducing information to/from optical disk of different standards

In a double density CD for an optical pickup device including a laser with a wavelength of &lgr;&mgr;m and an objective lens (,) with a numerical aperture of NA, the expression 0.7<TP/(&lgr;/NA)<0.8, where TP is a track pitch in &mgr;m and/or the expression 0.40<L/(&lgr;/NA)<0.45, where L is a minimum pit length in &mgr;m are/is satisfied. Thus, jitter is suppressed and the reproduction characteristic is improved.

Recording medium and optical pickup device

An apparatus for discriminating optical disks has an optical pickup provided with an objective lens having an effective numerical aperture of 0.55 to 0.65, which can compatibly reproduce information from a CD and an SD. The apparatus discriminates presence/absence of waveforms of two focus error signals detected when the effective numerical aperture of the objective lens is set at 0.55 to 0.65 and 0.20 to 0.45 respectively in a process of performing focus servo control, thereby discriminating various types of optical disks from each other. Thus, optical disks having different substrate thicknesses, different track pitches, different minimum pit lengths and different reflectivity can be quickly and simply discriminated from each other.

Apparatus for discriminating optical recording media of different thicknesses from each other and reproducing information therefrom

The optical pickup device includes a two wavelength semiconductor laser (,) selectively generating a laser beam having the wavelength of 635 nm and laser beam having the wavelength of 780 nm, a collimator lens (,), a hologram (,) formed on a surface of collimator lens (,), a polarizing glass (,) having an annular polarizing region (,) and an objective lens (,). Hologram (,) does not diffract the laser beam having the wavelength of 635 nm, and diffracts outward the laser beam having the wavelength of 780 nm. Therefore, virtual light source of the laser beam having the wavelength of 780 nm comes closer to the collimator lens (,) than the light source of the laser beam having the wavelength of 635 nm. Therefore, objective lens (,) focuses the laser beam having the wavelength of 635 nm on a recording surface of a transparent substrate (,) of a DVD, and focuses the laser beam having the wavelength of 780 nm on a recording surface of a transparent substrate (,) of a CD-R. Accordingly, the optical pickup device is capable of reproducing both DVD and CD-R having transparent substrates of different thicknesses.

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Hashima, Japan

Yoichi Tsuchiya