Abstract: In a disk recorder, unintended radial portions of a transducer or head, herein termed "skating", is rapidly controlled and stopped before the transducer or head can hit a crash stop. Even when a braking operation is effected in the wrong direction, the skating compensation reverses the braking operation for rapidly stopping the radial motion of a transducer. A pair of clamp circuits are electrically interposed between the servo actuator drive signal generation and a run-out compensation circuit such that the clamping operation does not alter the run-out compensation. The sequences of machine states for effecting the state accommodation are described.

Abstract: An optical apparatus for an optical information recording medium including a light source, two acoustooptical elements for modulating the light beam emitted from the light source and an objective lens for focusing the light beam emitted from the acoustooptical elements to the optical information recording medium, the acoustooptical elements being provided in an optical path extending from the light source to the objective lens arranged such that directions of travel of supersonic waves generated in the respective acoustooptical elements are crossed to each other.

Abstract: A WORM data storage medium includes primary and secondary data storage areas in which data and pointers to allocated but unwritten update areas are written. Original and updated data is written in a write sequence or chain of primary data areas separated by branched secondary data storage areas. The most recent updated data is found in a two level search of primary and then secondary data storage areas in order to save time by searching only those secondary areas where the most recent update exist.

Abstract: An optical information recording medium in which pre-pits longer than the diameter of a reproducing radiation spot and pre-pits shorter than the diameter of the reproducing radiation spot coexist, the width W of the pre-pit longer than the diameter of the reproducing radiation spot being formed with a value satisfying a relation of .PHI./4<W<.PHI./3, wherein .PHI.

Abstract: A track-seeking apparatus of a disk recorder employs a track-crossing sensor to produce track-crossing signals. An oscillator is slaved to the sensor for supplying substitute track-crossing pulses in the absence of the sensor providing such pulses or when the radial velocity exceeds a threshold velocity. A velocity profile means alters the oscillator frequency so that the oscillator produces track-crossing pulses in accordance with the profile.

Abstract: A recording/reproduction head incorporates an optical system which produces two light spots on an optical disk at positions spaced out from each other by, for example, half the radial span of the effective area of the disk. In recording or reproducing information using the two light spots, the inner light spot is moved to an unused track area provided in the innermost section of the disk, an auto-focusing servo system for the inner light spot is started, a control track provided near the unused area is read to judge the compatibility of the disk, and, only when the disk compatibility is verified, the outer light spot is moved to an unused track area provided in the outermost section of the disk, and an auto-focusing servo system for the outer light spot is started by making reference to a signal to the already operating inner auto-focusing servo system.

Abstract: An optical head apparatus for optical disks has a recording and reading laser beam generator and a wavelength reducer including reducing the wavelength of light from the laser generator. The laser beam generator is a separate unit from the head slider portion, the two being connected by an optical fiber which is used to transmit the recording and reading laser light to the slider. This arrangement enables short-wavelength laser light below 550 nm to be used for writing and reading operations without increasing the weight of the slider, thereby offering high-speed access and high recording densities.

Abstract: The present is to provide an optical information recording/reproducing apparatus which includes a multi-beam optical head extremely reducible of generation of a tracking offset caused by the inclination of a disc or track follow-up, so that the spot-wobbling method and the push-pull method are used to fetch a tracking error signal with respect to one reading light beam, the reading light beam being tracking-controlled by use of the tracking error signal obtained by the spot-wobbling method and then the tracking control for other light beams is performed by use of both the tracking error signal obtained by the push-pull method and that obtained by the push-pull method with respect to the reproducing light beam.

Abstract: A circuit for detecting delete patterns of an optical disc, the delete pattern overwriting data on a sector of an optical disc to delete previously written data of the sector, the delete pattern having a predetermined pulse width, period and number of pulses. The read-out signal from the sector is digitized with a predetermined slice level. The delete pattern is detected from the digitized signal by measuring pulse width to determine if the delete pulse width is present, by measuring the period between the pulses to determine if the delete period is present, and by measuring the number of pulses to determine if the delete number of pulses is present. According to one or more of these determinations, the delete state of the sector may be detected. The false delete state caused by dust, etc.

Abstract: There is provided a tracking servo apparatus of a disk player comprising: off-track detecting means for detecting that an information reading spot of a pickup does not exist on an information recording track of a disk and for generating an off-track signal; and level control means for increasing an amplitude of a tracking error signal when the off-track signal exists, whereby the stable tracking servo operation can be executed.

Abstract: A separation type optical pickup device for an optical information reading/writing apparatus using an optical recording medium. The device comprises a fixed optical system and a movable optical system. The fixed optical system is unmovable with respect to the recording medium and includes a laser beam source and has an opening through which the laser beam is output. The movable optical system is movable with respect to the recording medium and has an opening through which the laser beam is transmitted from the fixed optical system and includes a light guide for guiding the laser beam to the recording medium in a form of a convergent beam focussed on a surface of the recording medium. An expansible hollow member interconnects the fixed optical system and movable optical system in a state wherein the openings of the two systems as well as an optical path of the laser beam between the openings are enclosed by the hollow member.

Abstract: A gain control device for controlling the loop gain of a servo tracking system which enables a beam spot formed on a photodisc through an objective lens to trace a track on the disc. The gain control device opens the tracking servo loop and applied a drive signal to a lens actuator so as to move the objective lens across the tracks thereby generating tracking error signals. The device samples the tracking error signals and detects the amplitudes of these signals, and controls the loop gain such that the detected amplitudes fall within a predetermined allowable range.