Abstract: An optical disc system includes an optical disc which is formatted to store data in sectors. A tracking error signal is monitored and if the tracking error signal exceeds a predetermined threshold level, the address information of a next sector following a target sector in which data is to be recorded or from which data is to be read out is read out. And, if the address information thus read out has been found to indicate an address which is consecutive to the address of the target sector, the occurrence of a tracking error is determined. On the other hand, if the address information thus read out has been found to indicate an address which is not consecutive to the address of the target sector, then the writing (recording) operation is terminated so as to prevent overwriting of data in an undesired sector.

Abstract: An information recording apparatus includes a record signal processor for converting information to be recorded into an analog signal having three levels or more, a laser beam source for emitting a laser beam whose power is modulated at multiple levels in accordance with the three levels or more of the processed signal, and an optical system for focusing/radiating the laser beam on an information recording medium. The information recording medium has a recording layer. The laser beam whose power is modulated at the multiple levels is radiated on the recording layer. As a result, a plurality of phases having different crystallinities are obtained in a radiated portion in accordance with the laser power, and hence multi-level information is recorded in the data recording medium. The recorded information can be reproduced by detecting optical characteristics in these phases.

Abstract: An optical pickup apparatus is disclosed which comprises an optical detector formed on a substrate for detecting light reflected by a recording medium, a pattern formed on the substrate, a first block on which the substrate is fixed, a first reference surface formed on the first block substantially in parallel with an optical axis of the light to be detected, a second block arranged to be movable so as to be adjusted in a plane perpendicular to the optical axis and to support the first block, a second reference surface formed on the second block so as to correspondingly contact with the first reference surface; and a relay substrate fixed on the second block and electrically connected to the pattern.

Abstract: Optical disk player with tilt servo including means wherein the transfer frequency characteristic of a feedback circuit for controlling a tilt adjust mechanism is changed to a wide bandwidth transfer characteristic while in a search operation mode, and is changed to a narrow bandwidth transfer characteristic while in a play operation mode. Accordingly, the transfer frequency characteristic of the feedback circuit in the tilt servo system is changed according to the operation mode of the disk player, so that a suitable loop characteristic is selected for the tilt servo system.

Abstract: A track-jump device for a disc drive apparatus for jump from one track to a neighboring track on a disc-like recording medium. A tracking error signal S.sub.TE, an on-track signal S.sub.OT whose phase is deviated by 90.degree. relative to the tracking error signal according to displacement in the direction of track width and which exhibits a peak value when it is on the track, a signal S.sub.TE having a phase opposite to the tracking error signal, and signal S.sub.OT having a phase opposite to the on-track signal are successively switched by a switch (20) and are sent to a tracking drive circuit (27) to effect the track-jump. The servo operation is continued even during the track-jump, and the servo loop is not interrupted. Therefore, track-jump is effected while maintaining advantage in regard to safety, reproducibility, and compatability of pickups.

Abstract: A height adjusting device for adjusting the height of a pickup, comprises a support mechanism for supporting the pickup on the carriage in a manner that a position of the pickup along the axis of rotation of the turntable of the optical disc player is adjustable and an adjusting device for driving the support mechanism to adjust the position of the pickup. The adjusting device generates a height position signal indicative of the position of the pickup and the support mechanism is driven in response to the magnitude of the height position signal only when the magnitude of the height position signal is greater than a predetermined level. According to the other aspect of the invention, a compensated height position signal is generated by superimposing a compensating signal indicative of the position of the optical system of the pickup relative to the housing of the pickup on the height position signal, and the support mechanism is driven in response to the magnitude of the compensated height position signal.

Abstract: An information recording/reproducing apparatus includes an optical head for projecting a light spot onto an optical disk, a fine actuator for causing a light spot to track a track of the optical disk, a coarse actuator for moving the light spot over a recording region of the optical disk, a movement detector for detecting a moving distance of the fine actuator and outputting a detection signal, and a driving circuit for adding the output signal from the movement detector and a drive signal for driving the fine actuator and forming a drive signal for driving the coarse actuator on the basis of the sum signal.

Abstract: An optical pickup apparatus in which a laser beam reflected from an optical memory medium is separated and incident to a light-receiving element having a plurality of divided light-receiving faces and a focusing error signal is formed on the basis of a difference signal provided by a predetermined combination of light-receiving signals outputted from the respective light-receiving faces of the light-receiving element, comprises a bias signal forming device for forming a bias signal in accordance with a reflectance ratio of the optical memory medium based on a sum of the light-receiving signals outputted from the respective light-receiving faces of the light-receiving element; and a device for superimposing the bias signal on the focusing error signal in an accessing stand-by state with respect to the optical memory medium.

Abstract: The present invention relates to a laser reproducing apparatus which reproduces recorded data recorded on a recording medium such as an optical disc, a magneto-optical disc or the like by the irradiation of a laser beam, in which the current value of a driving signal which drives a laser diode (12) is set near a value at which there is the least interference with the laser beam is by reflected-back light from the recording medium, and the irradiation by the laser beam from the laser diode (12) at the thus set current value is intermittently carried out at predetermined intervals. Also, the duration of lock pulse of this laser beam is selected to be a duration in which writing on the recording medium (11) cannot be carried out by the thus set current value. Thus, the influence exerted on the laser beam by the reflected-back light from the recording medium (11) is small so that the data can be reproduced satisfactorily.

Abstract: An optical read-write apparatus for reading and writing information in tracks on an optical medium such as an optical disk has two or more beam sources for producing light beams with different wavelengths, and corresponding dichroic mirrors mounted in the path of the beams. Each of the dichroic mirrors reflects light of the wavelength of one of the beams and transmits light of other wavelengths. Piezoelectric transducers are provided for tilting one or more of the dichroic mirrors to adjust the tracking of the beams. An objective lens receives the beams after reflection from the dichroic mirrors and focuses them onto the optical medium.

Abstract: A magneto-optical playback head which comprises a first optical waveguide facing to a light source at one end thereof and facing to a magneto-optical recording medium at other end thereof for guiding an incident light beam to the magneto-optical recording medium, a second optical waveguide for guiding a light beam reflected from the magneto-optical recording medium to a photodetector provided at one end thereof, a polarizer provided for the first optical waveguide, and an analyzer provided for the second optical waveguide, the polarizer and the analyzer being formed by providing first and second conductive layers on the first and second optical waveguides, with first and second insulating buffer layers interposed therebetween, respectively.

Abstract: A clock signal producing circuit for a data storing and reproducing system in which a reference clock signal having a predetermined frequency is generated, a first sync-signal detection signal is generated when the time between two adjacent pulses in the input signal which is measured by the reference clock signal becomes equal to the predetermined reference value, the clock edge pulse is separated from the input signal using the first sync-signal detection signal and then outputted, and a reproducing clock signal having a predetermined frequency coinciding with the generating timing of the separated clock edge pulse is generated.

Abstract: An optical disk apparatus detects the speed of movement a laser beam gathered and focused by an objective lens from an optical disk. In a coarse access mode, speed control data is read out of a speed control table based upon the number of tracks corresponding to the difference between the present track and a target track. A linear motor, or an optical head coupled with the motor, is then moved in accordance with a difference between the present speed signal as detected and the speed control signal as read out. In a fine access mode, an objective contained in the optical head is moved in accordance with a difference between the present speed signal and the speed control signal.

Abstract: An information processing apparatus includes a main base and a drive base on which support frames are erected to face each other. A pair of parallel guide shafts are supported on the frames and extend in the radial direction of an optical disk. An optical head is supported by the guide shafts to be movable along the shafts. Insulating tape is wound around each end of the guide shaft to electrically insulate the head from the base, thereby preventing external noise from being transmitted to the head via the base. The drive base is further insulated from the main base by insulating seals interposed between the main base and the drive base and by insulating collars through which screws attach the drive base to the main base.

Abstract: An actuator rotatable about a support shaft rectilinearly movable along axis of a shaft and rotatably movable about the shaft includes a cylindrical magnet extending about the shaft. The cylindrical magnet has a plurality of poles in the radial direction and magnetized boundaries between poles of opposite polarity extending in a circumferential direction of the magnet and extending in an axial direction of the magnet. A plurality of yokes are provided to define magnetic poles coupled in facing relationship with the magnetic boundaries of a cylindrical magnet and having coils coupled thereto to define the magnetic poles.

Abstract: An optical head device for use in recording and/or reproduction of information comprises a light beam generating portion, a lens element for causing a light beam obtained from the light beam generating portion to impinge upon a record medium and receiving the light beam from the recording medium, and a photodetecting portion to which the light beam from the record medium received by the lens element is guided and which has three photosensitive elements separated from each other by a couple of parallel dividing portions and disposed to form a common light receiving plane on which a beam spot is formed by the light beam guided to the photodetecting portion for detecting the light beam guided to the photodetecting portion to produce respective detection output signals from which a tracking error signal is produced, wherein each of the parallel dividing portions extends along a direction selected to be at an angle within an angle rqnge of 0 to 90 degrees to a direction of movement of a diffraction pattern appeari

Abstract: An optical pickup device includes a light source for emitting light beam onto a recording medium. A lens is provided in an optical path between the light source and the recording medium. The lens converges the light beam to create a focusing spot on the recording medium. A tracking error detector receives a light beam reflected from the recording detector also receives a reflected light beam to detect a focusing error. A controller receives an output from the tracking error detector and the focusing error detector to produce a tracking error correction signal and a focusing error correction signal. A deflection angle adjuster is provided in the optical path and is responsive to the tracking error correction signal. The angle adjuster adjusts a deflection angle of the light beam. A refractive index adjuster is provided in the optical path and is responsive to the focusing error correction signal. The refractive index adjuster adjusts a refractive index of the light beam.

Abstract: An improved optical head for reading information recorded on a reflected medium. The optical head uses a hologram lens assembly having a transparent plate and a hologram lens, the transparent plate being obliquely positioned relative to a forward and a return beam paths. The transparent plate corrects beam aberrations in a laser beam emitted by a semiconductor laser on the forward beam path. The hologram lens diffracts the laser beam on the return beam path onto a photodetector. Both the transparent plate and the hologram lens add beam aberrations to the defracted laser beam on the return beam path for tracking purposes. The hologram lens assembly may also include a second hologram lens, preferably a three beam diffraction grating, for tracking purposes. The hologram lens and the diffraction grating may be located on the obliquely positioned transparent plate or on other transparent plates.

Abstract: A recording and reproducing device providing control data recording area on erasable type optical recording medium wherein control data are recorded thereof, characterized in that there is provided a control data recording area forming device for forming control data recording areas having more than two control recording blocks which in turn have more than one recording unit. The control data can be recorded independently. A control data updating device records new control data in the control data recording blocks which were the ones not previously being updated with control data, thereby allowing this device to minimize damage caused by electrical power failure.

Abstract: In an apparatus for searching a desired track of a recording carrier by transferring and controlling the reproduction position of the pickup for reproducing the signal recorded on a recording carrier on the basis of reference transfer information, the traveling load is measured, and the value of the reference transfer information is corrected according to this measured value, so that the desired track may be searched stably. The transfer motor is driven so that the reproduction position may move at a constant velocity, and the traveling load is measured. The transfer motor is driven so that the moving speed of the reproduction position or the time for moving a specified distance may be predetermined specific value, and by this driving signal, the value corresponding to the traveling load is determined.