Ricoh Company, Ltd.

Masami Emoto

Yoshitaka Takahashi

Hiroshi Gotoh

Hiroshi Akiyama

Hideo Inuzuka

Masanobu Nishimiya

Hiroshi Koide

Akihiko Okamoto

Hiroyuki Kiguchi

Kiyoshi Yokomori

Syuichi Honda

Shoji Kuroishi

Tsuguo Kimura

Shiro Yamamoto

Small-sized and light-weighted optical pickup apparatus capable of eliminating the effect due to the flaring light rays and performing the signal detection of high reliability is provided. In the apparatus, the quarter-wave (&#x3bb;/4) plate and the reflection-type birefringent prime provided with the deflecting function of deflecting the reflection light rays reflected on the optical information recording medium and the light rays flux separating function of separating the reflected light rays from the outgoing light rays are disposed in the optical path between the semiconductor laser constructing the optical pickup portion and the objective lens, and the light-receiving element for receiving the reflection light rays from the optical information recording medium which are defleced and separated by the reflection-type birefringent prism is disposed on a single (same) substrate together with the semiconductor laser.

Optical pickup apparatus

Small-sized and light-weighted optical pickup apparatus capable of eliminating the effect due to the flaring light rays and performing the signal detection of high reliability is provided. In the apparatus, the quarter-wave (.lambda./4) plate and the reflection-type birefringent prime provided with the deflecting function of deflecting the reflection light rays reflected on the optical information recording medium and the light rays flux separating function of separating the reflected light rays from the outgoing light rays are disposed in the optical path between the semiconductor laser constructing the optical pickup portion and the objective lens, and the light-receiving element for receiving the reflection light rays from the optical information recording medium which are defleced and separated by the reflection-type birefringent prism is disposed on a single (same) substrate together with the semiconductor laser.

An optical pickup device includes an optical system which forms a main spot and a set of sub-spots on an optical disk by a beam of light passing the optical system. A photodetector unit outputs first signals in response to a reflection beam from the main spot, and outputs second signals in response to reflection beams from the sub-spots. A tracking error detector includes a first detection circuit designed to output a first tracking error signal for a first track pitch, and a second detection circuit designed to output a second tracking error signal for a second track pitch different from the first track pitch. A switch selectively connects one of the first detection circuit and the second detection circuit to an output of the tracking error detector in response to a track pitch of the optical disk, so that one of the first and second tracking error signals appropriate for the track pitch of the optical disk is output.

Optical pickup device for detecting tracking error of optical disks with

Small-sized and light-weighted optical pickup apparatus capable of eliminating the effect due to the flaring light rays and performing the signal detection of high reliability is provided. In the apparatus, the quarter-wave (.lambda./4) plate and the reflection-type birefringent prism provided with the deflecting function of deflecting the reflection light rays reflected on the optical information recording medium and the light rays flux separating function of separating the reflected light rays from the outgoing light rays are disposed in the optical path between the semiconductor laser constructing the optical pickup portion and the objective lens, and the light-receiving element for receiving the reflection light rays from the optical information recording medium which are defleced and separated by the reflection-type birefringent prism is disposed on a single (same) substrate together with the semiconductor laser.

An optical data recording and reproduction apparatus which uses a semiconductor laser as a light source is disclosed. The half angle of light issuing from the laser in a junction direction of the laser and the focal length of a condenser lens adapted to focus a laser beam from the laser are adequately selected in such a manner as to satisfy a particular condition.

Optical data recording/reproduction apparatus for use with semiconductor

An optical pickup device for recording, reproducing or erasing an information, comprises a sole semiconductor laser beam source for emitting a luminous flux, a polarizer for receiving the luminous flux emitted from the sole semiconductor laser beam source and dividing the received luminous flux into a plurality of luminous fluxes, and a sole object lens for receiving a plurality of the divided luminous fluxes and converging each of a plurality of the received luminous fluxes on small spots on an optical information recording medium, respectively.

Optical pickup device

An optical pickup device for optically reproducing an information recorded on a recording medium of a magneto-optical disc or a write-only-read-many optical disc, includes a semiconductor laser, an objective lens for converging the laser light emitted by the laser on the recording medium, a photo-detector for detecting a light reflected from the recording medium, a beam splitter for leading the emitted light from the laser to the objective lens and for leading said light reflected by the recording medium to the photodetector, a first phase plate disposed between the beam splitter and the objective lens, a second phase plate disposed between the beam splitter and the photo-detector, and a rotator for rotate the first phase plate in such a manner than the beam splitter forbids to transmit the light reflected by the recording medium into the laser in a case where the recording medium is said write-only-read-many optical disc, and that the beam splitter allows to transmit the light reflected by the recording medium into the laser in a case where the recording medium is the magneto-optical disc.

Optical pickup device with dual-mode drive mechanism

An apparatus for recording and reproducing optical information comprises a laser beam source for emitting a laser beam; a collimator lens for forming light emitted from the laser beam source as an approximately parallel light beam; an objective lens for converging the approximately parallel light beam from the collimator lens in the shape of a spot on a recording face of an optical information recording medium; a device for recording and reproducing the optical information by converging the laser beam in the shape of a spot by the objective lens on the recording face of the optical information recording medium; a prism symmetrically arranged with respect to an optical axis in an optical path from the collimator lens to the objective lens; and a device for making a parallel light beam from the collimator lens through the prism incident to the objective lens so as to provide a light intensity distribution in which the light intensity in a peripheral portion of the optical axis is larger than that on the optical axis.

Recording and reproducing optical information device which converts the

An optical pick-up device suitable for use in an optical disk memory system includes a semiconductor laser unit which emits a laser light beam which, in turn, passes through a beam splitter, a quarter-wave plate, and an objective lens to impinge on an optical disc thereby forming a light spot thereon. The light is then reflected from the disc and this reflected light passes through the objective lens and the quarter-wave plate and its direction of advancement is altered by the beam splitter to move into a convergent lens. Then, as the reflected light further advances, it is partly blocked by a tracking error detecting sensor and the remaining non-blocked portion of the reflected light impinges upon a focusing error detecting sensor. The objective and convergent lenses have f.sub.0 and f.sub.1 as their focal distances, respectively, and, preferably, ratio f.sub.0 /f.sub.1 is set equal to or larger than approximately 10.

Optical pick-up device for both focus and error tracking detection

A knife edge type focus detection method for optics associated with an optical pickup is disclosed. A light intercepting member is interposed between an object lens and a light receiving element for focus detection in order to cut 60-95% of a reflected flux for focus detection before the flux reaches the light receiving element. The intercepted part of the flux includes a light ray which propagates through the optical axis of the optics.

Focus detection method involving cutting more than half of light beam

An optical pickup for detecting a distance to an optical disk on which information is optically stored includes a tracking error detecting device for detecting a tracking error by receiving a part of the light reflected from the disk and a focusing error detecting device for detecting the remaining part of the light reflected from the disk, structured such that the tracking error detecting device receives 60% or more of the reflected light.

Optical pickup with a two-detector arrangement

Less than half of a laser beam reflected from an optical information storage medium through an objective lens is detected by a detector having two light detecting areas. The sum of output signals from the light detecting areas of the detector is employed to detect when the objective lenas enters a focusing range. The difference between the output signals is employed to detect when the laser beam is focused on the optical information storage medium.

Method and device for detecting focal point

A photosensitive member is subject to a slitwise exposure. An imaging lens system is displaced in accordance with the magnitude of a magnification being utilized during a copying process which is switched. Disposed adjacent to the end face of a lens in the imaging lens system is at least one rectangular light shield member so that its lengthwise dimension corresponds to a slitwise scan direction. The light shield member is movable into or out of a light flux which is utilized for purpose of exposure, and is integral with the imaging lens system as the latter is displaced in accordance with a magnification being utilized during a particular copying process. During a light shielding operation, the light shield member is adapted to be disposed within or wedged partly into the light flux of exposure. As the copying magnification is switched, the amount of exposure light which is cut off by the light shield member changes, whereby the distribution of exposure light in the slit-shaped exposure station is made uniform as viewed lengthwise of the exposure station.

Exposure process for use in a variable magnification copying machine

A developing system is provided for a copying process such as an electrophotographic copying process in which a developer is supplied to the surface of a member which is formed with an electrostatic latent image to provide developing thereof. An electrode is disposed opposite the surface of the member with the developer interposed therebetween, and the induction potential of the electrode is maintained below a given value by means of a constant voltage element. The potential of the electrode is induced by either the image portion of the member's surface having the electrostatic latent image or by an unexposed, separate charged portion thereof.

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Yokohama, Japan

Masami Emoto