Abstract: In a process for producing vinyl chloride polymers including polymerization of vinyl chloride or a monomer mixture containing it in an aqueous medium using a polymerization initiator, the polymerization is carried out in the presence of a chelating agent, The chelating agent is capable of chelating iron (II) and iron (III). This process makes it possible to prevent polymer scales from adhering to, e.g. baffle surfaces facing inner walls of the polymerization vessel, which has been hitherto difficult to do so, and less cause initial discoloration of polymer products to improve quality. It is more effective to use a polymerization vessel previously provided with coating films of a polymer scale preventive agent on the inner walls of the polymerization vessel and the other portions with which monomers come into contact in the course of polymerization.

Abstract: An information reproducing apparatus for reproducing information by moving a magnetic wall along an information track on a recording medium. The apparatus includes an optical system for irradiating the recording medium with a light spot of an oval shape having a longer axis and a shorter axis, of which the longer axis is substantially parallel to the information track and a ratio of the longer axis to the shorter axis is at least 1.4, and a movement device for performing relative movement between the light spot and the recording medium.

Abstract: In a signal reproducing apparatus, information is reproduced by moving a magnetic wall on a magnetic recording medium while effecting relative movement between a light spot and the medium. A light spot is irradiated for forming a temperature distribution for moving the magnetic wall on the medium. A differential detecting unit takes a positive or negative value in accordance with a direction of magnetization in the light spot. An edge detecting unit takes a positive or negative value in accordance with directions of magnetization, before and after the magnetic wall as a boundary, in the relative moving direction in the light spot. A reproduction signal is generated on the basis of the detection result from the differential detecting unit and the detection result from the edge detecting unit.

Abstract: In a magnetooptical information recording-reproducing apparatus, recording of information is performed such that a laser beam is irradiated on a magnetooptical information recording medium via an optical head while applying a magnetic field to the beam irradiated portion of the recording medium onto which information pits are formed by utilizing the difference in the direction of magnetization thereof. The magnetooptical information recording-reproducing apparatus is provided with a band-like shielding plate which is arranged in an optical path of a reflected light from the recording medium upon application of the laser beam thereto in a direction perpendicular to tracks of the recording medium. Reproduction of information recorded on the recording medium is effected by detecting the beam which is not shielded by the shielding plate by use of a photodetector.

Abstract: An optical information recording medium includes a base, a reflecting layer formed on the base, a second layer formed parallel to the first reflecting layer at a predetermined distance from the same, and a recording layer formed between the first and second reflecting layers. The recording layer has an array of a plurality of cells having different refractive indices which are changed when irradiated with a light beam. The intensity of the light beam is modulated according to information. Irradiating the recording layer with the modulated light beam causes changes in the refractive index according to the intensity of the light beam. In another aspect, the wavelength of the light beam is changed within a predetermined range including at least one wavelength at which multiple interference occurs between the first and second reflecting layers with respect to each cell. The wavelength of light which has effective reflecting multiple interference is detected.

Abstract: In an optical head for radiating a light spot on a magneto-optical recording medium and detecting light received via the medium, there are provided a light source, a condenser lens for condensing light from the light source, a photodetector, and a deflecting device. The photodetector detects interference light between light generated by a magneto-optical effect of the medium and light generated by diffraction on a curved surface of the condenser lens. The deflecting device is arranged between the light source and the recording medium. The deflecting device includes a beam splitter with polarized light splitting characteristics and functions to deflect the light from the light source toward the recording medium.

Abstract: An optical information recording and/or reproducing apparatus includes an irradiating device including an objective lens, having a curved surface, for irradiating a recording light beam to a magnetooptical recording medium having at least two magnetic layers, which are a recording layer and a reproduction layer, and which are exchanged-coupled to each other, and a magnetic layer for controlling the exchange-coupling force to block the exchange-coupling force between the recording and reproduction layers, a device for applying an external magnetic field modulated according to an information signal to be recorded on the beam irradiated portion of the recording medium to record information on the recording layer and to orient magnetization of the reproduction layer in a direction parallel to the external magnetic field, a splitting device including a polarizing beam splitter for splitting at least light produced by a magnetooptic effect of the recording medium and light produced by diffraction at the curved surf

Abstract: An optical head of the present invention applies p-polarized light from a semiconductor laser chip to a magneto-optical disk in the form of a spot through a collimator lens and an objective. The optical head has a polarized-light separating hologram device for separating only an s-polarized light component from the reflected light. A hologram formed on the hologram device has two polarized-light separating surfaces divided by a line in the direction corresponding to the information track direction. Beams separated on the separating surfaces are guided to two information-reproducing photodetectors, respectively. A transparent cover of a semiconductor laser apparatus is provided with a separating hologram. A beam separated on the hologram is guided to a multi-division photodetector used for auto-focusing and auto-tracking operations. The information-reproducing photodetectors, the multi-division photodetector, and the semiconductor laser chip are formed on a common substrate.

Abstract: A magneto-optical disk according to the present invention has a transmission directory and a reception directory. An image to be transmitted is stored under the transmission directory as a single file, while a received image is stored under the reception directory as a single file. The operator designates a desired file stored under each of the directories for printing or transmission.

Abstract: An optical information recording/reproducing apparatus is disclosed. In the apparatus, a light beam polarized in a predetermined direction is irradiated onto an opto-magnetic recording medium to which a pre-determined magnetic field is applied. The light beam from the recording medium is condensed by the optical device and the condenced light beam is detected by the two-division detector. The two-division detector has a division line extending in a direction perpendicular to tracks on the recording medium. According to the apparatus, crosstalks and jitters can be eliminated and reproduction with high reliability can be realized.

Abstract: A minute light spot is irradiated on an information track on a recording surface of a recording medium from an optical head. When reproducing an information mark train recorded on the recording surface by the mark position recording method, light reflected by or transmitted through the recording medium is guided to a divided photosensor having a division line extending in a direction perpendicular to the track. A plurality of outputs from the divided photosensor is arithmetically processed to thereby detect the central position of the information mark.

Abstract: An information processing method and system in which coded or incomplete information is transmitted through a space or through a predetermined transmission line and is received by a user. A program or data needed to demodulate the information is read out from a recording medium, and the received information is demodulated using the read out program or data.

Abstract: A stereoscopic image processing apparatus for processing a stereoscopic image signal for a stereoscopic image which is composed of a plurality of images is arranged to receive a plurality of image signals for the plurality of images, to time-base-compress the image signals received, to form a composite image signal by combining the time-base-compressed image signals, to multiplex an information signal for information which is other than images but corresponds to the contents of the plurality of images, and to output the composite image signal to a transmission route. The arrangement enables the apparatus to combine the plurality of image signals for the images forming the stereoscopic image and to transmit the composite image signal together with the information signal for information which is other than images but corresponds to the content of the plurality of images.

Abstract: In an optical information recording/reproducing apparatus, the reproduction of information is performed as following manner. A light spot is formed on a recording medium on which information is recorded so that a phase of light reflected by a small region as an information pit is different from a phase of light reflected by other regions. Upon scanning the recording medium with the light spot, a leading edge and a trailing edge of the information pit in the scanning direction are respectively detected. A detection signal for the leading edge of the information pit and a detection signal for the trailing edge of the information pit are synthesized to effect the reproduction of information.

Abstract: An apparatus for recording and reproducing information on and from optical or opto-magnetic information recording media is disclosed. The apparatus comprises an irradiation device for irradiating a light beam polarized in a predetermined direction to an opto-magnetic recording medium an, application device for applying a predetermined magnetic field to the recording medium, an optical device for condensing the light beam obtained through the recording medium, and a detector for detecting the light beam condensed by the optical device. The detector has an effective light receiving surface almost equal to the airy disk size determined by the resolving power of the optical device. The apparatus precisely detects edges of information magnetic domains by using the S-polarized component produced by the opto-magnetic recording medium under the magnetic Kerr effect.

Abstract: An optical information recording and/or reproducing apparatus includes an irradiating device for irradiating light polarized in a predetermined direction onto a magnetooptical recording medium having a plurality of tracks, the irradiating device includes an objective lens, having a curved surface, for converging the light irradiated onto the recording medium to form a micro spot, an applying device for applying a predetermined magnetic field to the recording medium and a detecting device for detecting interference light caused by interference of light produced by a magnetooptic effect of the recording medium and light produced by diffraction at the curved surface of the lens, and for reproducing recording information.

Abstract: Information represented by an arrangement of codes of three or more kinds is recorded on a recording medium having a track in the following manner. The codes of the information are caused to correspond to information pits of three or more kinds respectively. The information pit corresponding to each code is formed on the track so as to be arranged along the track. Each information pit is recognized by the length thereof along the longitudinal direction of the track and the distance between the center of the pit in the longitudinal direction of the track and a reference position determined by a reference clock.

Abstract: An optical head includes an irradiating device for irradiating a recording medium with a light beam, a separating device disposed in an optical path between the recording medium and the irradiating device, which is provided for separating a portion of the light beam traveling from the irradiating device to the recording medium, and a detecting device for detecting the portion of the beam separated by the separating device, which has a plurality of sensor portions.

Abstract: A light beam is applied to an information recording medium to record information. A light amount of the light beam reflected by the recording medium is detected simultaneously with the recording of information. A defect of the recording medium is detected by comparing the detected light amount with a reference value. When a degree of the detected defect exceeds a predetermined level, the information is rerecorded on another portion of the recording medium.

Abstract: An information reproducing method comprises a reading out step for reading out information added with an error correction code from a recording medium, a correcting step for correcting errors of the information read out, and a generating step for generating a warning when the number of errors of the readout information lies within a correctable range and is a predetermined value or more.