Abstract: In a fine-focus actuator, the lens is coupled to a base by extension members. The extension members are rotatably coupled to the base and extend beyond the base. A counter-weight, positioned on the extension members, provides, in the presence of an external inertial force, a torque balancing the torque imposed on the lens holder by the external force. The counter-weight can include elements of the actuator such as magnets, etc.

Abstract: This high-density optical data storage unit comprises a storage medium supported on a mechanically stable substrate, and a read/write arrangement employing a plurality of laser light sources and an interrogation light source. The laser light sources are designed as laser diodes attached to a substrate and optically aligned with an equal plurality of microlenses integrated in a first transparent layer. The read/write arrangement further comprises at least one second transparent layer, and an optional semitransparent conductive coating, said layer or said coating carrying a plurality of particulate protrusions which are also aligned with said diodes and said microlenses, said storage medium and said read/write arrangement being maintained in a mutually parallel alignment with a gap in between having a width of less than 100 nm. The protrusions in combination with the laser light sources produce dints in the medium which are representative of the data to be stored.

Abstract: A data recording method by which data of a compact disk can be recorded well onto a magneto-optic disk of the ISO format. Data of a compact disk are recorded onto a 5-inch magneto-optic disk (ISO format) of the 512 bytes/sector type of the CS system. The sector size of the magneto-optic disk is 610 bytes. Data included in one sector (98 frames) of the compact disk are 2,352 bytes and subcodings of P to W are 96 bytes. Data for one sector are divided into data groups A to H to construct a data format. A CRC is added to each data group. Further, a parity 2 (Reed-Solomon code) is added. Data (3,050 bytes) for one sector of the compact disk to which the CRCs, parities and so forth are added are recorded across 5 sectors of the magneto-optic disk. Data of a compact disk can be recorded onto a magneto-optic disk having a different sector size, and since error correction codes or error detection codes are added using the remaining area, the data can be recorded with a high degree of accuracy.

Abstract: With a dye recording layer having an index of refraction n of 2.0 to 2.6 formed on a substrate, that portion of the recording layer disposed in a groove is used as a recording track by restricting the groove to a width W.sub.G of 0.38 to 0.45 .mu.m and a depth D.sub.G of 1000 to 1700 .ANG. and that portion of the recording layer in the groove to a thickness T.sub.G of at least 2000 .ANG. for 2.0.ltoreq.n.ltoreq.2.3 or to W.sub.G of 0.38 to 0.45 .mu.m, D.sub.G of 1000 to 2300 .ANG., and T.sub.G of at least 2500 .ANG. for 2.3<n.ltoreq.2.6. Reproduction is performed by means of a CD player which is adapted to perform tracking control by detecting a tracking error signal by the differential phase technique. There is obtained a tracking control loop gain of -2 dB or higher relative to that of commercially available CD, ensuring stable and accurate tracking control.

Abstract: In a head driving device having an optical head for erasing, recording and reproducing information, a carriage adapted to move in a radial direction of a disk as an information recording carrier together with the optical head, and voice coils attached to the carriage and imparting a thrust to the carriage in cooperation with a magnetic circuit, wherein tracking for a disk track deflection is performed by only a linear actuator comprising the magnetic circuit and the voice coils, a working center line of forces applied to the voice coils is set as so as to extend on the disk side with respect to the center of gravity of the moving portion. By so doing, a tracking servo system does not become unstable even when the working center line of forces exerted on the voice coils and the center of gravity of the moving portion are deviated from each other.

Abstract: In an optical information recording/reproducing apparatus to stop recording operation upon detecting an error in access operation to a target track, when making the access operation to the target track, if an abnormality is detected in the target track or some track in the neighborhood of the target track during a period of time from an access to the track in the neighborhood of the target track until reaching the target track, information is not recorded on the target track and the occurrence of an abnormality is informed to a host computer.

Abstract: The present invention includes a comparator that inputs a tracking error signal through one input terminal thereof, and a control circuit for producing a control signal that varies the reference level E of the comparator depending on an ROT signal which represents the rotational frequency of an optical disk. The control circuit varies the reference level E of the comparator depending on the rotational frequency of an optical disk. The comparator compares the varied reference level E with the tracking error signal, and outputs an off-track signal accordingly.

Abstract: The present invention senses angular acceleration of a Head Disk Assembly ("HDA") in a disk drive servo system and provides an acceleration feedback signal. A filter network filters the acceleration feedback signal and supplies a filtered signal for nullifying tracking error caused by shock, vibration and windup disturbances to the system.

Abstract: A device for accessing and following tracks on a surface of mobile media on which data is optically readable and writable by a laser beam. The device includes at least one optical head made of a rigid carriage which enables a laser beam (F) to access the track. A lens is rigidly linked to the rigid carriage (3) and focuses the laser beam on the surface of the mobile data medium. A return mirror is rigidly linked to the rigid carriage to direct the laser beam towards the lens. At least one motor coil allows movements of the carriage to focus the laser beam. A mirror which is not fixed to the optical head allows the laser beam to be directed towards the optical head, and a motor coil allows the mirror to pivot. Also means are provided for detecting and correcting any decentering of the beam in relation to the axis perpendicular to the plane of a pupil of the lens and passing through its center.

Abstract: An optical head system designed to accomplish an information recording and/or reproduction from opposite disc surfaces of an optical disc with the use of a single light source. The optical head system comprises a source of light for providing a linearly polarized beam of light; a collimator lens for collimating the linearly polarized beam of light into a collimated beam of light; a polarizing direction rotating unit for arbitrarily varying a direction of linear polarization of said beam of light; a polarizing beam splitter for dividing the beam, whose direction of linear polarization has been varied, into first and second beam components; and objective lenses for focusing the first and second beam components into respective penciles of light which are projected onto first and second, opposite disc surfaces of an optical disc or one disc surfaces of respective first and second optical discs.

Abstract: A method of and apparatus for reproducing data from a recording medium on which data is recorded as an arrangement of pits of predetermined lengths, formed at intervals, the pits including at least two kinds of pits differing in the level of a detection signal generated when the pits are detected, and the interval between the pits having at least two kinds of values. A signal subjected to modulation by the pits is read out from the medium. The read-out signal is compared with each of a plurality of reference values having different values. A clock signal is generated from a signal representing a comparison of the read-out signal with a smallest reference value of the plurality of reference values. The interval between the pits is detected from the read-out signal using the generated clock signal as a reference. Data is reproduced from the result of the comparison and the detected interval between the pits.

Abstract: An analog-to-digital converter executes analog-to-digital conversion of a first analog video signal at a predetermined sampling frequency "fs". A time base converter converts a time base of an output signal from the analog-to-digital converter at a predetermined time base conversion frequency "ftci". A digital output signal from the time base converter is converted into a corresponding second analog video signal in response to a clock signal of a frequency corresponding to the frequency "ftci". The second analog video signal is converted into an FM video signal recorded on a video region of an optical disk. A binary audio digital signal is converted into a multi-level form digital audio signal. The binary audio digital signal has a data rate corresponding to the frequency "ftci". The multi-level form digital audio signal has a data rate "ftci/n" and 2.sup.n discrete amplitude levels where "n" denotes a predetermined integer.

Abstract: An integrated optic head contains a planar and a channel waveguide, a waveguide condensing lens, and integrated waveguide photodetectors. The main portion of the beam returning from the disk is focused by the lens onto an integrated waveguide photodetector to provide the data signal. A smaller portion of the beam is sampled by channel waveguide Mach-Zehnder (MZ) interferometers that measure the beam wavefront curvature to provide the focus error signal (FES). Additional channel waveguides provide reference signals for the interferometers and provide a means of measuring the tracking error signal (TES). The TES method includes subtracting light detected by one channel waveguide detector from light detected by another, which difference is the tracking error. The FES method includes obtaining the difference in the ratios of the light emanating from two interferometers divided by the light emanating from their respective channel waveguides, which difference in ratios is the focus error.

Abstract: A data reproducing device for reproducing a positional information track formed in the longitudinal direction of a magnetic tape according to the present invention is capable of easily correcting regenerative positional information on the basis of count information even when the regenerative information is not obtained from the positional information tack by obtaining the count information consisting of the number so updating operations of positional information in accordance with a first clock generated based on the regenerative positional information acquired from the positional information track formed in the longitudinal direction of the magnetic tape and with a second clock generated based on rotation frequencies of tape reels for driving the magnetic tape.

Abstract: An optical disk apparatus in which a head is accommodated in a movable part which moves the head along a guide shaft in a radial direction of an optical disk. The guide shaft is engageable with the movable part and extends in the radial direction of the optical disk. The optical disk apparatus has a guide shaft compression mechanism which applies a compression force toward the movable part, which force is distributed, approximately uniformly, along the radial direction of the optical disk, to the guide shaft so that the movable part can be properly engaged with the guide shaft so as to move smoothly and stably along the guide shaft in the radial direction of the optical disk.

Abstract: An information recording device for recording digital information at a higher bit rate than that at which it is received. The difference in bit rate is compensated by an input buffer memory, read-out of a packet of information stored therein and recording thereof being periodically interrupted so as to maintain the filling level within a predetermined range. During each recording interruption, the recorded information pattern corresponding to the last recorded packet of information is read-out from the record carrier and the read-out signal is analyzed by an analysis circuit to derive an indication signal indicative of recording quality. The indication signal can be used to optimize the write parameters of the recording device, and also to determine whether re-recording of any or all of the last already recorded information packet should be performed before resuming read-out and recording of subsequent information packets from the buffer memory.

Abstract: A subcode reading apparatus for a compact disc player, designed to automatically read subcode data recorded on a compact disc without depending on a system controller, which includes a timing control circuit for storing in a memory the subcode data of successive blocks outputted from a CD digital signal processing circuit according to a command signal from the system controller. According to the present invention, the efficiency of the system controller can be increased and the overall construction of the system may be simplified.

Abstract: The present invention is directed to a writable optical disk recording apparatus in which an output power of a laser beam is controlled even during a recording period. During a calibration mode, a reproduced (reflected) signal from a matrix circuit (12) is supplied to level hold circuits (37), (38). The level hold circuits (37), (38) are controlled at predetermined timings relative to recording EFM (eight-to-fourteen modulated) signals of bit lengths (3T) and (11T) under the control of a microcomputer (CPU) (31). Signals from the level hold circuits (37), (38) are supplied to a calculating circuit (39) which calculates, for example, a difference or ratio between the two signals. A calculated value is stored in a memory (40). The value stored in the memory (40) and a value newly calculated by the calculating circuit (39) during EFM data recording are compared with each other by a subtracting circuit (41).

Abstract: The present invention relates to video recording and playback techniques and devices which create relative movement between a laser and an optical medium such as a flexible optical tape to permit the recording of different bandwidth signals. Further, the present invention relates to video recording and playback techniques and devices which optimize relative movement between a laser source and the optical medium in a cost-effective manner.

Abstract: In a magnetic recording/playback system having a magnetic head drive device for moving a movable head disposed within and mounted to a rotating upper drum in parallel with the axis of the drum, and a fixed drum supporting the upper drum so that the upper drum can rotate, an AC magnetic field generator is disposed along the peripheral surfaces of the drums at a location at which the magnetic tape is not wrapped on the drums. The AC magnetic field generator applies an AC magnetic field to the movable head that varies in the direction of the axis of the drums. Information on the position of the movable head is detected in accordance with the detection signal of the AC magnetic field derived by the movable head and the position of the movable head is controlled by feeding the detected positional infromation back to the magnetic head driving device.