Abstract: An optical pickup for reading information recorded on a recording surface of an optical information storage medium such as a compact disc or a laser video disc has a light beam source for emitting a linear light beam, and an optical system including an objective lens for converging the linear light beam as a linear image on the recording surface and collecting and emitting a light beam reflected from the recording surface.

Abstract: An optical recording medium information reproducing apparatus comprises; an optical system irradiating a light beam onto an optical recording medium in such a manner that the formed light spot covering a plurality of mark regions such as a pit and a land formed on and along the track of the medium; a second optical system of image formation for forming real images for the mark regions and the track to make an image surface by receiving a reflected light from the light spot; photodetecters for detecting the real images with a plurality of light receiving areas arranged along the real images of the mark regions and the track; and a processing circuit for computing the output signal of the photodetecters at a signal representing a length of each mark region in the track direction. Therefore, an information signal recorded on the recording medium is exactly reproduced without any adverse influence due to variations of the time base caused by rotational variations or the like of the spindle motor.

Abstract: An optical pickup device for writing or reading data from an optical information recording medium has a recording layer whose state changes in response to a density of intensity of an irradiated light beam and a track being used for a tracking servo control system. The device includes a first light spot irradiating element for irradiating a writing or reading light beam onto the recording layer to form a writing or reading spot and a second light spot irradiating element for irradiating at least one controlling light beam onto the recording layer to form a controlling spot having a major axis extending along the track and being longer than a transverse axis perpendicular to the major axis within a level of luminous flux density keeping an original state of the recording layer, whereby a tracking servo control signal having a sufficient level is obtained.

Abstract: An optical pickup apparatus including: an irradiation optical system for irradiating a light beam to at least one track of a recording medium carrying a recorded signal to be read, an image formation device for preforming an image formation of a real image for the recorded signal or track of the recording medium to make an image surface by using a reflected light from an irradiated portion of the light beam, and a photodetector for detecting the reflected light and having an optical receiving element disposed on the image surface. The optical receiving element has at least one first optical receiving element for tracking control which is bisected in a track image direction formed on the image surface such that the first optical receiving element has a width in a perpendicular direction to the track direction smaller than a distance represented by twice a track pitch in a track image formed on the first optical receiving element less a width of the track image.

Abstract: Optical disk information recording apparatus and reproducing apparatus are designed to efficiently improve the transfer rate in information recording and reproduction, and have compatibility with the existing recording apparatus and reproducing apparatus using a single light beam while keeping the disk form with a single spiral track structure. Beam spots are simultaneously irradiated on a plurality of different radial positions on a disk at a pitch of a predetermined number of tracks to independently record various information signals, and the optical head is allowed to jump over a predetermined number of tracks every time the disk makes a predetermined number of turns.

Abstract: An optical information recording medium configured to prevent signal reproduction due to intermodulation as well as to ensure a compatibility to players that involve read lights with different wavelengths and improved data transfer rate with higher information recording density. The optical information recording medium comprises a first recording layer for reflecting first incident light of a first wavelength to change an optical characteristic thereof and passing second incident light of a second wavelength different from the first wavelength, and a second recording layer for reflecting the second incident light to change an optical characteristic thereof, the first recording layer and the second recording layer are laminated in the order of the first and second recording layers from a side where the first incident light enters.

Abstract: A method of optically reproducing information from an optical recording medium on which concave or convex signal pits are formed, is provided with the steps of: irradiating each of pit edge portions of one signal pit which are opposed to each other, with a reading light respectively; detecting a reflection light from each of pit edge portions, separately, to output two detection signals indicating detected positions of the pit edge portions with respect to one signal pit; and reproducing one information recorded in one signal pit on the basis of the two detection signals.

Abstract: Optical disk information recording apparatus and reproducing apparatus are designed to efficiently improve the transfer rate in information recording and reproduction, and have compatibility with the existing recording apparatus and reproducing apparatus using a single light beam while keeping the disk form with a single spiral track structure. Beam spots are simultaneously irradiated on a plurality of different radial positions on a disk at a pitch of a predetermined number of tracks to independently record various information signals, and the optical head is allowed to jump over a predetermined number of tracks every time the disk makes a predetermined number of turns.

Abstract: An optical disc has recorded information and is irradiated with a laser beam at a first spot for reading information recorded on the disc and at a second spot. The second spot has such an area that intensity of light reflected at the second spot does not change with change of the recorded information. A first photodetector is provided for detecting intensity of light reflected on the first spot, and a second photodetector is provided for detecting intensity of light reflected on the second spot. A subtracter is provided for producing the difference between outputs of the first photodetector and the second photodetector and an alternating current detector is provided for producing an output at a slice level where the difference of the subtracter becomes zero.

Abstract: A plurality of tracks are spirally arranged in a group on an optical disc. The tracks in the group are simultaneously radiated by laser beams. Adjacent tracks in the group are disposed at a radial distance d1, and adjacent spots of the laser beams on the tracks are disposed at a radial distance ds which is smaller than the distance d1.

Abstract: An optical disk includes a recording medium having a disk shape, and a plurality of signal pit strings formed on the recording medium and arranged in a circumferential direction of the optical disk. Each of the signal pit strings includes a plurality of signal pits arranged in a line in a radial direction of the optical disk. An optical pickup apparatus includes a photodetector having a plurality of photoelectric elements. A light spot is sequentially projected onto the signal pit strings, and a reflected light therefrom is converged by an objective lens. An image formed by the objective lens is detected by the photodetector located in an image forming position of the objective lens. The unit information pieces contained in one of the signal pit strings are simultaneously read by the photoelectric elements. In this manner, the signal pit strings are sequentially read while the optical disk is being rotated.

Abstract: An information signal recording apparatus has an information signal supply source for supplying an information signal at a predetermined transfer rate and a memory device for storing the information signal. An information signal stored in the memory device, which stores information signals at a predetermined transfer rate, is read out and recorded on a disk at a rate higher than the predetermined transfer rate, and, every time a predetermined length of an information signal is recorded, the predetermined length of the information signal, recorded immediately before reading, is read out at a rate higher than the predetermined transfer rate to thereby verify the recorded information signal. This allows read-verification of written information without losing the real time performance, and ensures successive recording of information even when an error is found in the information.

Abstract: A crosstalk level detector has a processing circuit for determining the level of crosstalk of a signal read by an information reproducing system from an information storage medium with information recorded in its tracks. The processing circuit compares levels of reference signal components contained in the read signal and produced from adjacent signal tracks at positions aligned in a direction normal to the tracks, and calculates the crosstalk level based on the compared levels. The reference signal components may be derived from a signal recorded in the information stored medium, such as a horizontal synchronizing signal recorded in an optical video disk.

Abstract: The present invention relates to a photo-detecting device which records/reproduces a signal such as visual information on/from an information recording device such as an optical disk, and more particularly to a structure of a photo detector that receives light reflected from the optical disk, and a method for processing the signal outputted therefrom, and it is an objective of the present invention to obtain a reproduced signal having a good SN ratio without any effect of other signals by a rather simple structure.

Abstract: An optical information recording medium, to and from which information can be recorded or reproduced at a high density, uses more number of kinds of pits than those of a conventional optical disc. A reproducing apparatus for such a medium also is devised. Information is recorded onto the recording medium by using a plurality of pit lengths which are obtained by dividing a whole frequency band below a cut-off frequency of MTF characteristic of a reproducing system into a plurality of bands in correspondence to the band characteristic and by allocating a plurality of spatial frequencies to the divided bands.

Abstract: An optical pickup apparatus reproduces signals recorded on an optical disk, which has a signal track in which a plurality of signal pit strings are arranged in a circumferential direction of the optical disk, each of the signal pit strings including a plurality of signal pits arranged in a line in a radial direction of the optical disk, the optical disk being rotated at a speed v relative to the optical pickup apparatus.

Abstract: An optical pickup has a light source for generating a first light having a longer wavelength and a second light having a shorter wavelength, an objective, and a phase hologram disposed between the light source and the objective. The objective is designed to have a larger spherical aberration for the first light than a spherical aberration for the second light. The phase hologram is arranged to give a phase difference of an integer multiple of 2.pi. for the second light. The phase hologram is further arranged so that a spherical aberration given to the first light has an opposite polarity to the polarity of the spherical aberration given by the objective.

Abstract: An optical recording medium player reproduces a signal with lower intermodulation even in case of a reading laser beam for an optical recording medium is used having a wavelength different from a standard wavelength. The player comprises photoelectric converting means having a light receiving surface divided into central and peripheral regions, amplifying means for amplifying the output signals from the divided receiving surfaces, adding means for adding the outputs of each amplifying means, discriminating means for discriminating the type of a recording medium being played, and adjusting means for adjusting the sensitivities of signal processing systems including photoelectric converting means in accordance with the result of discrimination. Even in case the wavelength of reading laser beam of optical recording medium is different from the wavelength of reading laser beam as defined for a standard recording medium, it is possible to obtain a reproduction signal with less intermodulation.

Abstract: A pickup device can detect the frequency (pit length) recorded in the recording medium, and read out data signals from the optical disk at high S/N. Further, the data read speed is considerably increased since it is possible to concurrently read data signals from the tracks. In a pickup device, a linear light beam emitted from a light source is projected onto an optical disk through a condenser lens so as to form an image thereon, which is long enough to cover three recording tracks on a recording medium. Signal light reflected on the recording medium is imaged on a photo detector consisting of an array of detecting elements, and is detected and output by and from the photo detector. A frequency analyzer unit analyzes the frequencies of the detected signals. A computing circuit calculates the output values for each analyzed frequency. Accordingly, it is possible to separate the frequencies of the recording tracks from each other.

Abstract: A recording medium has a flat surface on which information is optically recorded. The recording medium rotates about a rotational axis normal to the flat surface. The recording medium has a first track extending around the rotational axis and a second track extending around the rotational axis along the first track. The second track has a plurality of segments, each of which being connected to adjacent segments and having a longitudinal direction different from the adjacent segments such that the second track extends in a zigzag fashion along the first track. The longitudinal direction the respective segments are oriented substantially toward the first track.