Mitsubishi Denki Kabushiki Kaisha

Mitsubishi Denki Kabushiki

Hitoshi Imai

Kazuo Okada

Michihiro Tadokoro

Kimiyuki Koyanagi

Michihiro Takokoro

Nobuyoshi Andou

Ryuichiro Arai

An optical recording and reproducing apparatus for optically recording and reproducing information on and from a disk includes a light source for generating a parallel beam. A movable optical system condenses the parallel beam from the light source on the disk, splits the beam into two different beams, and moves in the radial direction of the disk. A split-beam detecting device has two light receiving surfaces which receive part of the two different beams obtained in the movable optical system. A and a control device effects tracking control by moving the movable optical system in the radial direction of the disk in accordance with respective detection signals output from the two light receiving surfaces.

Optical recording and reproducing apparatus having a pickup head

The optical recording/reproducing apparatus provided with a dividing optical element which divides a part of the light from a light source and projects the divided light to a moving stage on which an objective lens is mounted, a reflecting optical element which is mounted on the moving stage and reflects the projected light from the dividing optical element, and a photodetector which detects the reflected light from the reflecting optical element, wherein the deviation amount of the moving stage from a reference position is detected on the basis of output of the photodetector. Since the condition when the reflected light is incident upon the photodetector is changed in consequence to the positional deviation of the reflecting optical element as the moving stage is moved, the deviation amount of the moving stage is detected on the basis of the output of the photodetector. The deviation amount of the moving stage can be detected at all times, thereby achieving good tracking control.

Apparatus for detecting positional deviation of a moving stage in a

A photodetector fixing mechanism for fixing a photodetector, which detects reflected beams from a recording medium, on a base plate with screws wherein caul portions integrally formed with the base plate sandwich a mounting member mounted with the positioned photodetector with the base plate to prevent the mounting member from being in contact with the screw heads so as not to cause skid of the mounting member by turns of the screws.

Means for securing a photodetector to a base plate or the like

The present invention relates to an optical recording and/or reproducing apparatus which optically carries out operations of recording and/or reproducing of information on a data carrier, by irradiating a beam from an optical head to the data carrier. In the apparatus according to the present invention, the angle between the optical axis of the beam from the optical head and the surface of said data carrier is detected, and a temperature adjusting device brings about a difference in temperature between both surfaces of the data carrier on the basis of the detected result in respect to the angle. Then, the difference in temperature generates a thermal strain, and this thermal strain functions to cancel the strain which the data carrier has previously had. As a result, the surface of the data carrier is kept on a level, so that this surface can be vertical to the optical axis of the beam from the optical head. Therefore, in the optical recording and/or reproducing apparatus, easily maintained is the right angles between the surface of the data carrier and the optical axis of the beam, and the mechanism for focalizing the beam can be simplified to miniaturize the optical head. Furthermore, no mechanism for making the optical head oscillate is required, as a result, a high-speed accessibility is obtained.

Optical recording and/or reproducing apparatus having a temperature

A magneto-optic recording a reproducing apparatus including a magneto-optic information-carrying medium having three magnetic layers. A magnetic bias field is generatedd by a third layer which is premagnetized in the direction parallel to the thickness thereof. A second layer is magnetized by a magnetizing unit. The laser beam incident on the layers is controlled to three intensities for writing and reading information.

Magneto-optic recording and reproducing apparatus including a multiple

A magneto-optic information-carrying medium comprises three magnetic layers. A magnetic bias field is generated by a third layer which is premagnetized in the direction parallel to the thickness thereof.

Magneto-optic information-carrying medium including three magnetic layers

The storage medium for an optical data storage system is a contiguous laminate formed by a plurality of layers of photochemical hole burning material, such layers individually exhibiting inhomogeneous absorption spectrum characteristics spanning different, successive wavelength ranges. This arrangement greatly expands the cumulative or overall absorption band of the storage medium available for laser hole burning to implement data bit writing, and thus increases the storage density at each memory site.

Optical data storage system with wavelength selective laminate

An information-carrying medium having the form of a disc is rotated around a central axis. The temperature of the disc is controlled by a temperature-adjusting element facing the surface of the disc.

Optical reading or writing apparatus

Information is recorded by creating recording hole at a predetermined wavelength position on a memory element with a characteristic of wavelength selective optical data storage. Because the memory element is pit-like, it causes diffraction of a light beam transmitted through or reflected by it. The diffracted beams are detected for positioning a beam spot right on the selected memory element.

Wavelength selective optical data storage system

A recording medium for wavelength selective optical data storage has at least one memory element on which information is recorded by creating recording holes on the absorption spectrum thereof. The spectrum has at least one prerecorded hole for identifying the wavelength positions of the recording holes.

The present invention relates to an optical head for optically recording or reproducing information. In the optical head of the present invention a holder is provided with an optical element fixedly attached thereto. The holder is axially movable in a guide bore of a housing member and a tapped hole is formed in the circumference of the housing member which hole does not reach the guide bore so as to create a deformable bottom hole portion. When a screw is screwed into the tapped hole it presses against and deforms the bottom hole portion so as to engage the holder. Accordingly, with the optical head according to the present invention, the rotational torque generated when the screw is rotated is absorbed in the bottom portion of the tapped hole, so that the holder is not moved when the screw is screwed into the tapped hole, whereby the optical element fixedly disposed on the holder can be easily positioned at an appointed position.

Apparatus for positioning an optical element

A light beam emitted from a source is focused on an object. The beam reflected by the object passes through an optical member and is detected by a photodetector. The optical member has a reflecting surface the reflectivity of which varies continuously with respect to the angle of incidence.

Focus detecting apparatus utilizing reflecting surface having variable

An optical head for optical recording and reproducing system comprising a light source, a first optical means for introducing a light beam from the light source into a guide groove formed in a recording surface of an information carrier, and a second optical means for separating a reflected light beam reflected from the guide groove from the light beam from the light source. The optical head also comprises an optical element having formed thereon at its center a cylindrical surface and on both sides slanted surfaces for dividing the reflected light beam into three, and a light receiving element having at least three light receiving units for receiving the respective light beams divided into three by the optical element.

Growing community of inventors

Amagasaki, Japan

Hitoshi Imai