Mitsubishi Denki Kabushiki Kaisha

Mitsubishi Denki K.k.

Kazuo Okada

Michihiro Tadokoro

Hitoshi Imai

Masatomo Seya

Mitsushige Kondo

Kenjiro Kime

Motomu Yoshimura

Mitsuo Maeda

Mitsushige Kondou

Nobuo Takeshita

Shinsuke Shikama

Teruo Fujita

Hiroo Shimegi

Kazuo Hirasawa

Nobumasa Egashira

Michihiro Takokoro

Fumiaki Imado

An optical head for recording, reproducing or erasing data by emitting a light beam irradiated from a light source onto a recording medium. To reduce the height of the optical head, an optical axis shifting device is disposed between a light beam emitting device and a condensing device for condensing the light beam onto the recording medium. This optical axis shifting device shifts the first optical axis of the light beam from the light beam emitting device to a second optical axis positioned in parallel and spaced apart from each other. As the optical axis shifting device, there is preferable employed a prism having two reflecting faces lying in parallel, and the optical axis, after shifting is to be positioned downwardly of the position of the optical axis before shifting, thereby reducing the height of the optical head.

Optical head

A wavelength selective optical recording and reproducing method includes an optical recording and reproducing step of information composed of time series signals on a recording medium having recording tracks as position series signals with light having a variable wavelength while switching the wavelength between predetermined values.

Wavelength selective optical recording and reproducing method

An optical head for use in an optical information recording/reproducing apparatus includes an optical system comprising a plurality of optical elements including a light-emitting element, and a casing which securely mounts at least part of the optical elements. The casing is provided with a vibration damping material which is effective to damp vibrations of the casing.

Optical head for optical information recording/reproducing apparatus

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

A focusing error detecting apparatus comprises an objective lens system for focusing a ray flux on a surface of an optical recording disk, two photo detectors, an optical means including the lens system and a beam splitter, for focusing a ray flux reflected from the optical recording disk so that the ray flux comes to the middle of a space formed between the two photo detectors when the focal point is formed on the optical recording disk, a combination of two interruption/deflection elements and a control device for switching the ray flux transmitted from the optical recording disk at the two positions which correspond to said two photo detectors, two sampling/holding circuits respectively hold differences of output of the two photo detectors in correspondence to the switching operations of the interruption/deflection elements and the control device, and a subtracting circuit for outputting a focusing error signal on the basis of the outputs of the sampling/holding circuit.

Focusing error detecting apparatus with light switching and detector

Provided is an optical recording and reproducing apparatus in which a collimator lens collimates divergent light fluxes from a light source to emit parallel light fluxes and then an objective lens converges the parallel light fluxes onto an information carrier. The collimator lens comprises a first lens having a first predetermined focal distance and a second lens having a second predetermined focal distance which is longer than the first predetermined focal distance. The second lens can be moved in the optical-axis direction so as to adjust the relative position of the collimator lens and the light source.

Optical head including a collimator having lenses of different focal

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 apparatus for reproducing information from records made by an optical-wavelength-multiplexing method which includes a first medium acting as a data carrier which data can be recorded on and reproduced from by the optical-wavelength-multiplexing method and which further includes a second medium having the same characteristic as that of the first medium on which no records have been made, wherein components of light reflected or transmitted by the first and second mediums are then detected by a first and second photodetectors, respectively, and wherein the outputs of the first and second photodetectors are further processed so that a ground level of the 'reproduced signal' is adjusted to substantially constant value.

Apparatus for regenerating information from records made by

A wavelength selective optical recording and reproducing device has a reference wavelength in a marker hole of a medium. The optical detector is adapted to detect light which is reflected from or transmitted through the marker hole. A phase detector detects the phase of an output of the optical detector by using a high frequency signal as a reference to obtain a signal indicative of the deviation of the wavelength of the output from a desired wavelength. A wavelength regulator is responsive to the wavelength deviation to control the wavelength of the light source to be the desired wavelength.

Wavelength selective optical recording and reproducing device

An information-carrying medium with first, second and third ferromagnetic layers is enclosed in a housing, in which an initializing magnet is disposed. The second layer of the information-carrying medium is magnetized by the initializing magnet premagnetized in a uniform direction and is used as a bias layer.

Information-carrying medium equipment for magneto-optic reading and

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 first memory element and a second memory element have characteristics of wavelength selective optical data storage. Information is recorded on the first memory element by creating recording holes by a narrow band light beam at specific wavelength positions within a broad inhomogenous absorption line. The second element has at least one prerecorded hole at a specific wavelength position thereof for detecting the wavelength positions of the recording holes.

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Amagasaki, Japan

Kazuo Okada