Masahiro Ojima has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
Abstract: A record carrier for recording, reproducing and erasing information. A circular disc-like substrate has a recording layer thereon such that information is written onto the recording layer by changing the direction of magnetization. A guide groove of a plurality of tracks is formed in advance and extends in the radial direction with flat portions therebetween. Each flat portion between the tracks of the guide groove is divided into a plurality of sectors, each of which includes a header portion in which a header signal containing an address for distinguishing at least a respective sector is formed in advance with pits of a phase structure and a data portion adjacent to the header portion. The guide groove serves as an optical guide for a light beam which records, reproduces and erases information onto the data portion.
May 21, 1987
Date of Patent:
January 15, 1991
Atsushi Saito, Masahiro Ojima, Masaru Ito
Abstract: An optical information recording carrier which comprises an information recording film susceptible to a change in atomic arrangement upon exposure to a recording beam, a first transparent film for preventing diffusion of heat generated in the recording film upon exposure to the recording beam and provided on each side of the recording film, a second transparent film for diffusing the heat in the in-plane direction of the film and provided on at least one outside thereof, and an organic member further provided on at least one outside thereof, the recording beam being irradiated onto the recording film through the organic member has distinguished characteristics of repeated recordings and erasings.
Abstract: A magneto-optical recorder comprising an optical head for projecting a light beam on a magneto-optical recording medium so as to form a light spot thereon, a magnetic head disposed at a predetermined distance from the optical head and applying a magnetic field modulated according to information to be recorded to the magneto-optical recording medium; and light intensity controlling means for varying the intensity of the light spot, responding to at least one of a focusing error signal indicating deviations of the light spot from the magneto-optical recording medium and a position signal indicating the relative position of the magneto-optical recording medium and the optical head, wherein, even if the intensity of the magnetic field applied to the recording medium varies, depending on vertical oscillations of the recording medium or on the position of the light spot, influences of variations in the intensity of the applied magnetic field are compensated by varying the intensity of the light spot so that fluctua
Abstract: An information recording method and apparatus therefor utilizes an information recording medium having a recording film enabling reversible phase change. The information recording medium is irradiated with an energy beam while relatively moving the information recording medium and the energy beam so as to at least enable recording of information in accordance with phase state changes of the recording film caused by irradiation of the energy beam. The energy beam is modulated so that an intensity of the energy beam obtains a first level having a high power for one portion of coded data information to be recorded, obtains a second level different from the first level for a predetermined time for another portion of the coded data information, and then again obtains the first level to enable recording of the coded data information independently of a previous recording state on the information recording medium.
Abstract: Disclosed is a wavelength multiplexing optical recording apparatus comprising laser sources radiating a plurality of laser beams of different wavelengths, an optical system for focusing the laser beams, and an optical recording medium having a plurality of optical recording layers with wavelength sensitivities for selective recording by said laser beams focused by said optical system. The optical recording layers of recording medium are laminated with distances between adjacent layers being made consistent with biased focal positions of the laser beams attributable to the chromatic aberration of the optical system, so that the laser beams are focused on the optical recording layers of corresponding wavelength sensitivities.
Abstract: A semiconductor laser device utilizing at least a pair of semiconductor laser chips; and a fixing device for fixing the semiconductor laser chips so that electrode surfaces are approximately parallel and opposite to each other and the interval between light emitting spots of the semiconductor laser chips is small.
Abstract: An optical information recording apparatus, in which marks having a desired shape are recorded at desired positions, independently of the patterns of recording pulses, while canceling influences of the heat conduction from the mark, which has been directly previously recorded, by controlling the energy at the front end portion of laser light pulses, depending on the interval from the directly preceding pulse, when recording medium is irradiated with the laser light pulses corresponding to recording pulses so as to record information.
Abstract: A desired portion of information stored in the form of holes using hole burning phenomena is erased by irradiating a desired portion of a recording medium with light so as to erase desired holes. In this way it is possible to erase selectively only desired information among information stored in a PHB memory and further to rewrite information in the portion, where information has been erased.
Abstract: A semiconductor laser array device in which a single photodetector is provided near the exit ports on one side of the semiconductor laser array device that has a plurality of semiconductor lasers arranged close to each other, the light outputs from each of the laser light sources are detected in a time-sharing manner, and the corresponding lasers are controlled by feedback relying upon the detected signals, so that outputs of the lasers are stabilized.
Abstract: In an information recording apparatus according to this invention, since it is not necessary to dispose any differential circuit, which was required heretofore, it is possible to fabricate it with a low cost and its error rate is also very small.Furthermore, since the mean reflectivity on the recording track does almost not vary by the fact that information is recorded there, no tracking off-set or focusing off-set is produced. Thus effects of this invention are remarkable.
Abstract: In order to suppress laser noise, a semiconductor laser oscillating in a single mode under direct-current drive is driven by a signal with a high frequency current superposed on a direct current. In particular, the laser is driven to be brought into continuous wave pulsed oscillation at a pulse width of at most 1.2 ns to achieve the desired noise suppression.
Abstract: Method and apparatus for processing information on a recording member having a recording film capable of recording and erasing information in accordance with the change of a magnetizing direction, by utilizing a light induced thermo-magnetic effect, in which before the intensity of the laser light is switched at the high level eliminating the magnetization of the recording film in order to effect the recording and erasing operations by focusing the laser light on the recording film as a light spot, a magnetic field with the predetermined direction according to the recording and erasing operations is previously applied on the recording film, whereby the recording and erasing operations of the magnetized information can be effected with high speed and stably by applying the normal magnetic field in the direction according to the recording and erasing operations respectively.
Abstract: An optical head for a magneto-optical memory in which the major axis (the phase advance axis or phase lag axis) of optical anisotropy of a lens focusing a linearly polarized laser beam onto a magneto-optical recording medium is arranged to coincide with the direction of linear polarization of the laser beam incident upon the lens, thereby improving the extinction ratio.
Abstract: In a magneto-optical file memory wherein a storage medium having a vertical magnetic film is irradiated with a laser beam to reverse a magnetization direction of the magnetic film, thereby to write and/or erase information, and a rotation of polarizable face of reflected light from the storage medium is detected, thereby to reproduce information; a magneto-optical file memory wherein a sense of a leakage magnetic field of an actuator which controls an optical system for condensing the laser beam on the storage medium is set to be the same as a sense of initial magnetization of the magnetic film of the storage medium.
Abstract: An optical information storage system wherein information is read from a magneto-optical storage medium by indicating the storage medium with a first laser beam generated by a semiconductor laser and exploiting the self-coupling effect of the semiconductor laser in response to light reflected from the storage medium to generate a second laser beam. A Faraday rotator is disposed in an optical path along which the reflected light from the magneto-optical storage medium returns to the semiconductor laser and a polarization rotating angle of the Faraday rotator is selected so that the oscillating polarization plane of the semiconductor laser is changeable in dependence upon the perpendicular magnetization direction of the magneto-optical storage medium.
Abstract: An optical pickup wherein a semiconductor laser device for projecting a laser beam onto an optical disc is driven by a D.C. current and a high-frequency current superposed thereon, and the laser device oscillates in a multiple longitudinal mode.
Abstract: This invention relates to an apparatus for detecting magneto-optical anisotropy which can be utilized as an information reproduction apparatus for detecting information recorded on a magnetic medium. The apparatus consists of a light source (10), a magneto-optically anisotropic medium (20), a polarization analyzer (33A) and a light detector (34). To avoid the information reproduction by means of the linearly polarized light as in the prior art, the apparatus of the present invention reproduces the information using the light source (10) which generates the elliptically polarized light. This makes it possible to reproduce the information having a high signal-to-noise ratio.
Abstract: A recording medium having at least a first inorganic material layer which overlies a predetermined substrate and which exhibits a light absorptivity for projected light, and a recording layer which overlies the first inorganic material layer and whose principal component is an organic material. The first inorganic material layer contains at least one element selected from the group consisting of In, Bi, Te, Sb, Ge, Sn, Pb, Cr, Nb, Ni, Pd, Fe, Pt, Re, Ta, Th, Ti, Zr and Tl and the content of the element or elements is at least 65 atomic-%.Further, the first inorganic material layer may well be overlaid with a second inorganic material layer which exhibits a light transmissivity higher than that of this first inorganic material layer. Preferable as the material of the second inorganic material layer is an inorganic material which contains at least one element selected from the group consisting of In, Bi, Te, Sb, Pb, Ge and Sn and at least one element selected from the group consisting of S, Se and O.
Abstract: A recording member having a predetermined substrate, and a thin film which is formed on the substrate and which is formed with recesses or pits for recording information when irradiated with a working beam, characterized in that said thin film is formed of an inorganic material which contains at least arsenic, selenium and tellurium, and that a distribution of either of said Se and said Te decreases from a part near the surface of said thin film towards a central part thereof, while a distribution of said As increases from a part near the surface towards said central part, is disclosed. This recording member can afford a high signal-to-noise ratio and a long lifetime.
Abstract: An optical information processor comprising a semiconductor laser device which has a rectangular light emitting region, a disk, and an optical system which includes a prism for converting a non-circular beam emergent from the laser device into a circular beam, the circular beam being projected onto the disk by the optical system thereby to record or play back predetermined information.