Sanyo Electric Co., Ltd.

Other

Shuichi Ichiura

Yoichi Tsuchiya

Seiji Kajiyama

Yasuyuki Kanou

Osamu Ota

Hitoshi Terasaki

Koichi Tada

Masato Yamada

Hiroshi Watanabe

Naoyuki Takagi

Ken Hirose

Seizo Kato

Yasuyuki Kano

Shinichi Ohe

Yoshimoto Yamaguchi

Toshio Ito

Toshio Harada

Atsushi Yamaguchi

Masami Shimizu

Yoshihisa Suzuki

Yoshiaki Maeno

Katsutoshi Hibino

Masahiro Higuchi

Minoru Sato

Youichiro Goto

Tateo Toyama

Kiyotaka Eizumi

Shinji Kobayashi

Mikio Ichihashi

Yasuyuki Matsushita

Hitotoshi Kimura

Nobutoshi Oki

An optical pickup apparatus includes at least: a light emitting element capable of emitting at least first wavelength light and second wavelength light; and a diffraction grating configured to split the first wavelength light into at least a first main beam and a first sub-beam and to split the second wavelength light into at least a second main beam and a second sub-beam, a following expression (1) being satisfied: where: Ypis an interval between the first main beam and the first sub-beam when a first media corresponding to the first wavelength light is irradiated with the first main beam and the first sub-beam, and Ypis an interval between the second main beam and the second sub-beam when a second media corresponding to the second wavelength light is irradiated with the second main beam and the second sub-beam.

Optical pickup apparatus and disc apparatus including the same

An object of the present invention is to provide a detection device which does not cause the false detection by receiving laser light from an oncoming car. The pulse laser light modulated with a modulation pattern set every target position is irradiated at the target position from a laser irradiation portion. DSP (Digital Signal Processor) decides that there is an obstacle at the target position only when the modulation pattern of the pulse laser light emitted from the laser emitting portion matches with the modulation pattern of the pulse laser light received by the laser receiving portion. It is suppressed that the detection device misdetects the conditions of the target position when receiving laser light from an oncoming car or the like because modulation pattern of laser light from own does not match with modulation pattern of laser light from the oncoming car or the like.

Detection device for detecting conditions at a target position

A scan trajectory of a laser beam is controlled based on external signals each related to a driving direction and a driving speed, a result obtained by detection of an obstacle, and signals related to distances to the obstacle. For example, at the time of a right turn, a scan trajectory for increasing scan frequency on a portion shifted in a right-turn direction from a center axis in a driving direction is set. At the time of high-speed driving, a scan trajectory for increasing scan frequency on a center portion in the driving direction is set. When the obstacle is detected at a position corresponding to a distance shorter than a threshold distance, a scan trajectory for increasing scan frequency in the vicinity of the obstacle is set. Detection and monitoring are performed at the time of: changing of the driving direction, the high-speed driving, and the detection of the obstacle.

Detection device

A detection device detects an obstacle within a target region by setting the target region, setting a scan trajectory, and setting a pattern of an irradiation position of a laser beam within the target region based on a signal related to a moving state of the detection device or a moving object on which the detection device is mounted.

Detection device controlled by driving speed and driving direction

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

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

In order to reproduce signals from a double-layer optical disc having two signal recording surfaces, a focus jump that the focusing of an objective lens from the one signal recording surface to the other signal recording surface is quickly achieved, is necessary. When a focus error signal (FE) from a pickup ( ) reaches a predetermined threshold value (Vcomp), a deceleration signal for decelerating the objective lens ( ) is supplied to an actuator ( ). Preferably, a deceleration pulse voltage is lowered step by step. The deceleration pulse voltage is determined in accordance with the maximum value (DFEmax) of a differential focus error signal (DFE) generated by differentiating the focus error signal (FE). Preferably, the address seeking is done simultaneously with the focus jump. The focus jump is performed in accordance with the layer-to-layer distance which is measured beforehand. The focus jump is performed by using a lens ( ) having a controllable focal distance. Preferably, whether the layer is the first layer or the second layer is judged based on the reflected luminous power. If the focus error signal (FE) from the other layer is not obtained even when a certain time passages after the focus jump is started, the objective lens ( ) is moved in the reverse direction.

Optical disk device

Optical disc 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

An optical disk includes a track having a track pitch that is k times (0<k<1) the track pitch of a compact disk format. The track is formed by a pit having a pit length shorter than k times the pit length of the compact disk format. The track pitch P&mgr;m and shortest pit length L&mgr;m are set to satisfy the relationship of L<(A/1.6)&times;P where A&equals;(V/4.3218)&times;3 when a standard compact disk having linear velocity of V m/second is compressed. When the recording density is to be increased to two times that of the compact disk, the track pitch is set to approximately 0.9-1.4 &mgr;m, more preferably approximately 1.1-1.3 &mgr;m, and further preferably to approximately 1.2 &mgr;m. Since the track pitch is not compressed as much as the pit length in this optical disk, generation of crosstalk can be suppressed. Also, jitter in a reproduced signal can be suppressed since the track pitch is set to 1.2 &mgr;m or in the vicinity thereof.

Optical disk having high recording density

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.

Optical pickup device and wavelength selective diffraction grating

Growing community of inventors

Hashima, Japan

Shuichi Ichiura