Abstract: A method and apparatus is provided for reducing relaxation noise in a conducting medium. The device is fabricated by affixing two magnets at like, repelling poles; wrapping said magnets with a coil of wire in an orientation orthogonal to the interface between the joined magnets and the like poles of the magnets to form a magnetic unit; connecting said coil to a motor means, an electrical power supply means and a switch means; attaching a spindle to said motor means. The spindle receives said conducting medium. The apparatus can be in a housing. The conducting medium is placed on said spindle. By activating the device, a modulated magnetic electromagnetic field is created simultaneous to the spinning of the conducting medium. The information recording medium rotates through the modulated electromagnetic field, thereby reducing the relaxation noise.

Abstract: An optical pickup device capable of maintaining a sufficient amount of laser beam light when recording information on an optical disc and stabilizing the light emission of the semiconductor laser when reproducing information. Each optical component constituting an optical system for an optical pickup device used for both information recording and reproducing is coated with an antireflection film whose spectral reflectance changes in accordance with the wavelength of an incident light. The antireflection film has a high spectral reflectance at a shorter wavelength in the whole range of light emission wavelength covered by the semiconductor laser light source and a low spectral reflectance at a longer wavelength, and is formed on the incident surface or outgoing surface of at least one optical transparent element.

Abstract: Digital information is represented by surface steps orthogonal to the surface of a record carrier, said steps having a plurality of values between one tenth and 10,000 nanometers. The steps are read out by an optical differential interference method that is capable of resolving one tenth of a nanometer. The steps are written by a repeated masking and etching technique to form a master record carrier on glass from which a stamper is formed by molding and used to stamp replicate record carriers in polymeric material. In a different embodiment of the record carrier the surface steps are created by a modulated laser beam that ablates an integral number of layers from a pre-coated multilayer structure. In a third embodiment the data is represented by modulating the index of refraction between spots on a thin material film. The index difference is written optically. An extension to multiple thin film layers is also disclosed.

Abstract: A recording/reproduction of information is effected using a probe electrode arranged to oppose a recording medium. A distance between the probe electrode and the recording medium is controlled by applying a voltage therebetween. A current flowing through the probe electrode upon application of the voltage is detected while the scanning is performed with the probe electrode over the recording medium. A correlation between a signal output according to the current detection and a reference signal is obtained to produce a reproduction signal from which a noise component due to an influence of an atomic step present on a surface of the recording medium is removed. The reproduction of information is effected in accordance with the generated reproduction signal.

Abstract: A magneto-optic recording method and a magneto-optic recording apparatus in which a magneto-optic overwritable medium having two layers, which layers have different coercive force--temperature characteristics and are coupled by exchange interaction, is heated by applying a light beam while an external magnetic field is being applied to the medium and in which data coded to invariably have FALSE states between two TRUE states is turned into a light beam having dual power levels and recorded on the medium, the magneto-optic recording method including the steps of: forming record marks by heating the magneto-optic overwritable medium to a high temperature by means of a high light beam power associated with a FALSE state in the write data; and of heating the magneto-optic overwritable medium to a low temperature by means of a low light beam power associated with a TRUE state in the write data.

Abstract: A system for reducing noise in a data recording/play-back device includes an optical system for scanning a recording medium and providing first and second polarization signals. The polarization signals are added to provide an added signal. The added signal is differentiated to provide a noise reduction signal. The polarization signals are substracted to provide a difference signal. The differentiated signal is substracted from the difference signal to provide a data signal having a substantially reduced noise level.

Abstract: With an optical playback device, for example, with a compact disk player, care should be taken to see that the light beam scanning the data radiates as perpendicular as possible onto the disk. However, as a consequence of disk slap or chattering, the radial and the tangential angles alter during every revolution of the disk. As a result of the tolerances in the disk and the device, the optical axis deviates from the perpendicular in many cases. In order to regulate the radial angle .phi.R and the tangential angle .phi.T, under which the light beam strikes the disk, the data signal is demodulated in an amplitude demodulator. The regulating signal UR=C* sin .phi.* cos .alpha. for the radial angle .phi.R and the regulating signal UT=-C* cos .phi.* sin .alpha. for the tangential angle .phi.T are generated from the amplitude C and the phase position .phi. of the demodulated data signal.

Abstract: A method of reproducing information recorded on an optical recording medium includes the steps of directing a first reading optical beam and a second reading optical beam onto a recording portion on the optical recording medium to obtain a first electric output signal corresponding to the first beam interacting with the optical recording medium and a second electric output signal corresponding to the second beam interacting with the optical recording medium, and performing a non-linear operation and a linear-operation by using these first and second output signals, thereby obtaining an improved reproduced output signal.

Abstract: A semiconductor laser chip comprises a substrate and material layers successively formed on the substrate. The laser chip has an output cleavage face and emits an output laser beam which is inclined to the output cleavage face. The laser chip may be incorporated in a laser pickup device for optically reading information from an optical data carrier such as optical disk.

Abstract: A laser control system for use with an erasable optical disk device to minimize laser feedback during a recording operation. Focus control circuits are utilized to establish a slightly defocused condition prior to a recording operation and maintaining that slightly defocused condition throughout the recording operation. Defocusing the write beam significantly reduces feedback and thereby significantly increases pulse-to-pulse repeatability of the write pulse amplitude at the optical disk.

Abstract: A signal information recorded on a recording layer formed on a phase-change type optical disk is reproduced as a phase change. Laser light emitted from a laser light source is collimated to a reference light by a lens. The reference light is divided by a beam splitter into a first reference light and a second reference light. The first reference light is directed through a condenser lens to the recording layer of the optical disk. A reflection light from the recording layer is directed through the beam splitter and a second condenser lens to an optical detector. The second reference light is passed through a phase difference plate, a reflection mirror, the phase difference plate, the beam splitter and then through the second condenser lens to the optical detector as a phase shifted reference light.

Abstract: In an optical storage system, a non-signal radiation component from a laser unit which is leaves the optical path as a result of selection of a signal polarization component for interaction with the optical storage medium is applied to a first detector. The output electrical signal from the first detector is combined with the output electrical signal from the second detector to which the radiation component, which has interacted with the storage medium, is applied. The two electrical signals are combined in a manner to reduce the noise from the laser unit which is superimposed on the signal from the second detector. In the typical read/write head, the non-signal beam can be the deflected radiation from the beam splitter.

Abstract: A magneto-optical recording and/or reading-out apparatus can record and read out information on and from a magneto-optical recording medium by the use of a laser beam. The apparatus includes a reflected beam detector, a comparator operatively coupled with the reflected beam detector, and a judgment unit operatively coupled with the comparator. The reflected beam detector detects the quantity of a laser beam reflected from the magneto-optical recording medium during recording. The comparator compares the quantity of the reflected laser beam with at least one reference value during the recording, thereby detecting an abnormality in the reflected laser beam. The judgment unit judges whether an area of the magneto-optical recording medium which has caused the abnormality is practically usable, in accordance with an output from the comparator and data to be recorded on this area.

Abstract: A disk storage device includes a light source emitting a light, an objective lens for focusing the light on a surface of a recording film of a disk via a protection film protecting the recording film, and a motor for rotating the disk. A detector receives the light reflected by the surface of the recording film and reproduces information recorded on the recording film. The detector is located at a position where the following condition is satisfied:D.gtoreq.F.times.A.times..alpha.where D is the distance between the objective lens and the detector, F is the focal length of the objective lens, A is equal to F/t2 where t2 is the thickness of the protection film, and .alpha.is a constant equal to or greater than 1.0.

Abstract: The optical information recording and reproducing method and apparatus include a method for controlling a high frequency pulse current for driving a semiconductor laser device by which noise due to returning laser light is hardly produced, and an apparatus for increasing access speed owing to decrease in the weight of an optical pick-up movable part. Loser noise is suppressed satisfactorily by detecting the position of the optical pick-up movable part in a split optical system by means of a scale, and generating a pulse current for modulating the laser having a frequency optimum for reducing the laser noise to drive the semiconductor laser device.

Abstract: The invention relates to the reading of optical disks in which the recording is performed in volume in separate layers. Reading a bit recorded within the layers gives a signal with a background noise from all the adjacent bits illuminated by the read beam. In order to eliminate this background noise, the read beam is modulated in position about the bit to be read, either horizontally or vertically with respect to a recording level. The background noise remains unchanged but the signal from the bit being read becomes a periodic signal.

Abstract: A modulating signal is predistorted to linearize the output of an optical intensity modulator. The modulating signal is split into first and second paths. In the first path, the signal is phase shifted. In the second path, distortion components are introduced. The phase shifted signal from the first path is then combined with the distorted signal from the second path to provide a predistorted signal for use in modulating a light source. The distortion generator can comprise a diode pair coupled with opposite polarities in parallel. Both diodes are forward biased, and the pair is coupled in series with the input signal to provide the desired predistortion.

Abstract: A method and apparatus for reducing the number of errors generated when reading digital data stored on a recording medium such as film, the method comprising passing light of two different frequencies (i.e., two different frequency bands) through the film, one frequency being modulated by digital data stored on the film and the other being unaffected by the stored data. The light that is unaffected by the stored data is modulated by debris on the film such as dirt and is used to flag data bits that may be in error to thereby facilitate an error correction process. In the first disclosed embodiment the two frequencies of light are processed separately to obtain the digital data and error flags. A second embodiment combines all light passing through the film to produce digital information that includes error flags.

Abstract: A laser in a magneto optical recorder supplies a laser light beam to be used in processing signals to and from a magneto optical record member. The laser beam is split into two portions. A first portion is the data beam which is directed to impinge upon a magnetooptic storage member. A second portion is so-called wasted light which is directed away from the storage member. The wasted light is intercepted by a mirror and reflected into a beam splitter to phase-coherently combine with light reflected from the storage member for improving signal-to-noise ratio of the reflected storage member light beam. This action improves signal-to-noise ratio and enhances servo operation in the focusing position control of the optical head with respect to an optical storage medium.

Abstract: Provided is a signal reproducing circuit for an optical disc player including a multidivisional photodetector with photoelectric converting elements in a preceding side and photoelectric converting elements in a succeeding side relative to a proceeding direction of pits of an optical disc, a variable delay circuit for delaying outputs from the photoelectric converting elements in the preceding side, a circuit for detecting a time difference between an output from the photo electric converting elements in the succeeding side and an output from the variable delay circuit, and a circuit responsive to an output from the time difference detecting circuit for changing a delay time of the variable delaying circuit. The signal reproducing circuit further includes a circuit for amplifying and correcting high frequency components of signals reproduced by the photo detector in response to the output from the time difference detecting circuit.

Abstract: In a disk player, a tilt detection signal is generated corresponding to a tilt of a recording surface of a disk relative to a reference plane depending on a position of a pickup or a pickup radial position is generated. A reproduced video signal is passed through a noise reduction circuit having a transfer function which is changed in accordance with the tilt detection signal or the radial position signal so as to reduce a noise component. Accordingly, the influence of cross-talk on a picture caused by the tilt of the disk can be electrically reduced, and a complicated mechanism becomes unnecessary, so that it is possible to simplify the structure of the player. Moreover, it is not necessary to select a pickup in which the quantity of cross-talk is small against a tilt of a disk, so that it is possible to make the production cost low.

Abstract: A pick-up device which includes a light source and a condenser lens for effecting recording and reproduction of information by projecting a light beam as collected by the condenser lens onto a recording medium. A diffraction grating is provided between the light source and the condenser lens for dividing light returning from the recording medium by a diffraction grating so as to be directed to a photo-detector, to thereby obtain an optical detection signal.

Abstract: An apparatus for reproducing data from an optical disk by a light beam includes a housing which is movable in the readial direction of the optical disk. The housing includes a directing element for directing the light beam onto the optical disk, a detector for detecting the light beam from the optical disk so as to generate an electrical signal corresponding to the detected light beam, a dividing element for dividing the electrical signal generated by the detector into a low frequency component and a high frequency component, and an amplifier for amplifying the high frequency component divided by the dividing element. The reproducing apparatus further includes a moving element for moving the housing in radial direction of the optical disk, an adjuster for adjusting a distance of the directing element with respect to the optical disk in response to the low frequency component divided by the dividing element, and a reproducing circuit for reproducing data from the optical disk in response to the amplifier.

Abstract: An apparatus for recording information on an optical type recording medium alternately generates a binary signal of a first frequency and a binary signal of a second frequency lower than the first frequency, applies radiation to the medium and writes the binary signals of the first frequency and the second frequency into the medium, reproduces the binary signals of the first frequency and the second frequency written into the medium and converts them to electrical signals, AC-amplifies the electrical signals, detects the difference between the amplitude of the output of the AC amplifier of a level higher than a reference level, which corresponds to the first frequency and of a level lower than the reference level, which corresponds to the first frequency and outputs a detection signal, and responds to the detection signal to control the intensity of the radiation applied to the medium for writing.

Abstract: An optical pick-up for scanning a magneto-optically recorded disk in which the disk reflects a first principal beam onto a first photodetector. This first principal beam has a plane of polarization which is rotated in one direction. The recorded disk reflects a second principal beam onto a second photodetector. This second principal beam has a plane of polarization that is rotated in another direction. A data signal is generated from the difference between output photovoltages of the first and second photodetectors. A diffraction grating splits the main beam from a light emitting source, into the principal beams and into subsidiary beams. The main beam from the light emitting source is focused on the recorded disk through the diffraction grating. Auxiliary photovoltages are generated from the auxiliary beams, and these are subtracted for generating the data signal. The output voltage of the second photodetector has noise components that are in phase and which are generated by the main beam.

Abstract: A servo loop arrangement for the reproduction of data from a record medium has interleaved pulse trains of opposite polarity pulses applied to it to add to the servo loop control signal which undesirably includes an offset voltage. The resultant increasing opposite polarity changes in the control signal in successive pulse train intervals are threshold detected. The numbers of opposite polarity pulses required to reach the threshold values are compared and any difference in number is converted to a compensation signal which is added to the servo loop to compensate for the offset voltage.

Abstract: A system capable of retrieving, recording or erasing information from an optical recording medium such as an optical disk or card. Two or more light beams reflected from the optical memory are detected by a photodetector. A correction circuit processes the photoelectric signals received from the photodetector to correct for the effect of other than one light beam on the focusing of the system on the optical recording medium.

Abstract: An information signal recording medium reproducing apparatus comprises an equalizer supplied with a frequency modulated composite video signal picked up from an information signal recording medium, a frequency demodulator for frequency-demodulating an output signal of the equalizer into a composite video signal, a synchronizing signal separating circuit for separating a horizontal synchronizing signal from the composite video signal, and a switching signal generating circuit for forming a switching signal from the horizontal synchronizing signal.

Abstract: This invention is to provided in such an information recording apparatus in which when an exposing locus is formed on a film by irradiating on the film an exposing beam whose width is changed in response to an input audio signal, the average level positions of the exposing locus is controlled in response to the signal level of the input audio signal, a level detector circuit for comparing the input audio signal with a predetermined reference level signal, a continuous circuit for making the compared output from the level detector circuit continuous, a first integrating circuit for integrating the continuous output from the continuous circuit and a second integrating circuit for integrating the integrating outputs from the first integrating circuit and delivering the same as the average level position signals used upon the exposure and recording.

Abstract: An optical storage medium drive apparatus having a light beam source for recording information on an optical storage medium and reading out the recorded information from the storage medium by using a light beam. The apparatus has an optical head in which the light source is included for emitting a light beam, and a light detector for converting reflected light from the storage medium into an electric signal and an optical system for guiding the light beam from the light source to the optical storage medium and a reflected light beam from the optical storage medium to the light detector. The optical system has therein a light reflector for changing the direction of the light beam and which causes retardation of the light. An optical phase compensator is disposed on the optical path between the optical head and the optical storage medium for compensating for retardation of the light beam caused by the reflector.

Abstract: An optical information recording and reading apparatus checks the recording of information simultaneously with recording of said information by means of a recording laser beam by detecting a deflected portion of the reflected beam of the recording laser beam from an optical recording medium. An intensity differential signal is generated by monitoring different portions of the deflected portion of the reflected beam. The intensity differential signal is insensitive to intensity changes in the recording laser beam. The accuracy of the recorded information is determined by sensing the change of polarity of the intensity signal. An error signal is generated as a function of the polarity of the intensity differential signal to re-record information not recorded properly.

Abstract: The locally averaged or approximate D.C. value of a variable area optical sound track on a film is first determined, and this information is then used to control the width of a scanning slit at a playback station. The scanning slit width is reduced for small signals and increased for large signals, thereby reducing the amount of non-information bearing area on the film which is included in the scanned area. This in turn reduces the amount of noise from dirt and debris in the non-information bearing area, and by reducing the total amount of light transmitted through the film also lowers the level of quantum noise from the photodetector employed at the playback station.

Abstract: Optical data recording apparatus which enhances a playback signal by comparing the lengths of the lands on a recording medium with the lengths of the pits on it and changes the playback signal to represent equality between such lengths.

Abstract: To desensitize the write channel of a direct read after write optical memory from time dependent changes in the operating characteristics of the hardware and from time and position dependent variations in the performance characteristics of the recording medium, the present invention provides a real time feedback system for adjusting the output power of the write laser or similar source and/or for adjusting the modulation timing of the write beam so as to null out any unwanted dc component that is exhibited by the recorded data during the direct read after write process. In other words, the feedback stabilizes the timing of the transitions in the recorded data.

Abstract: An optical disc player comprises a rotating member for rotating the optical disc, an optical pickup member for reproducing a digital audio signal including an error correcting code such as the Reed-Solomon Code from the disc, an error correcting decoder for decoding the error correcting code so as to produce a corrected or interpolated digital audio signal and condition flag data indicating the correction of the digital audio signal, and a display for indicating the condition flag data as a stain or contamination condition of the disc.

Abstract: An optical pickup wherein a semiconductor laser device for projecting a laser beam onto an optical disc is driven by a D.C. current and a high-frequency current superposed thereon, and the laser device oscillates in a multiple longitudinal mode.