Abstract: Quantization noise due to analog-to-digital conversion may be larger than a noise component of an input signal, and therefore sufficient performance may not be obtained.

Abstract: An information recording device and method capable of forming a recording mark by suppressing thermal interference. The device applies a laser beam to a recording medium and forms a recording mark in accordance with a recording signal. The device includes a light source for emitting the laser beam, signal generation elements for generating a recording pulse signal according to the recording signal, and drive elements for driving the light source according to the recording pulse signal. The recording pulse signal has a mark period for forming the recording mark and a space period. The recording pulse signal makes the level in the entire space period equal to or shorter than a predetermined length and a part of the space period longer than the predetermined length to be off level. While the recording pulse signal is off level, the recording medium is cooled down, thereby suppressing the affect of thermal interference.

Abstract: A method and apparatus to record data on an optical recording medium include generating a recording waveform having an erase pattern comprising a multi-pulse having a high level which is higher than an erase power level and a low level which is lower than the erase power level. A power level of a leading one of the multi-pulse of the erase pattern and a power level between an end of the erase pattern and a start point of a leading pulse of a recording pattern are controlled to be the low level and the high level, respectively, the high level and the high level, respectively, the high level and the low level, respectively, or the low level and the low level, respectively.

Abstract: An information recording reproducing apparatus for recording and/or reproducing informations on and/or from an optical recording medium. The apparatus comprises a light source, at least two objective lenses corresponding to at least two kinds of optical recording media having different thicknesses of a protective layer, respectively, a rotatable holder for supporting these objective lenses, magnetically activatable selection elements for selecting these objective lenses in accordance with the optical recording medium, the light of the light source being illuminated on the optical recording medium through the objective lens selected by the magnetically activatable selection elements, thereby performing recording and/or reproducing of the information.

Abstract: In an optical recording and reproducing apparatus which forms at least first and second light spots on a track of an optical recording medium to record, reproduce or erase information, a movable range of the second light spot is limited to less than one half of a track pitch, normal to the track, from the track to prevent tracks other than a target track from being miserased, misrecorded or misreproduced. When a deviation of the second light spot from the target track exceeds a predetermined amount, light emission of the second light spot is stopped to prevent a track other than the target track from being miserased, misrecorded or misreproduced. When the deviation of the second light spot from the target track exceeds the predetermined amount, the second light spot is returned to a neutral position to prevent a track other than the target track from being miserased, misrecorded or misreproduced.

Abstract: An apparatus for eliminating tracking/focus crosstalk in optical and magnetooptical disk drive systems by only sampling the focus error signal on land areas between the grooves of the disk when seeking is described. A logic circuit responsive to the system's tracking error signal generates a pulsed sampling signal whenever the laser spot is positioned over land areas. This pulsed sampling signal is used to sample and hold the focus error signal during the time that the pulsed sampling signal is active.

Abstract: A control circuit for controlling the position of a head in an optical tape recording/reproducing device having a rotary optical head controls the position of the head at the instant that it faces the tape based upon a desired head position derived from a preceding period in which it was facing the tape. A head position error signal is sampled and added to a sample head position signal during a period when the head is facing the tape and is held during the time the head is not facing the tape. The instant the head begins to face the tape once again, this desired value that has been held is applied to the head in order to reduce the pull-in time of the control circuit and provide more time for information recording/reproduction during the time the rotary optical head is facing the tape.

Abstract: An information signal recording/reproducing apparatus includes a recording apparatus and a reproducing apparatus. The recording apparatus is arranged to record on a recording medium an information signal after angle-modulating the signal in such a way as to cause a signal corresponding to a timewise portion of the angle-modulated information signal to be in a given relation to a reference signal. The reproducing apparatus is arranged to angle-demodulate the angle-modulated information signal when it is reproduced from the recording medium, and to perform time base correction on the basis of the signal part of the angle-modulated information signal. Time base variations occurring during the reproduction can be accurately carried out by the arrangement without having any special signal added to the information signal during recording.

Abstract: An optical head device includes a tilt servo mechanism using photodetectors for detecting rays of light reflected from the recording surface of an optical disk. The rays of light are obtained from a laser diode used as a light source for information reproduction. According to one aspect; prisms are formed on the flange of a converging lens to refract peripheral portions of the light emitted from the laser diode for tilt detection. According to another aspect, secondary diffraction grating domains at the sides of the primary diffraction domain of a diffraction grating diffract peripheral portions of the emitted rays of light for tilt detection. According to another aspect, a mirror reflects peripheral portions of the emitted rays from the laser diode. According to a further aspect a mirror reflects the light from the laser diode passing through a beam splitter.

Abstract: A method and apparatus for transverse registration of image exposures on photoreceptive belts subject to lateral deviation from linear travel in which targets, corresponding in location to the image areas to be exposed, are used for the detection of lateral belt displacement and to control the transverse location of exposure scan. The targets are of a pattern defining a reference line and a line inclined with respect to the direction of belt travel so that the duration of time between passage of the target lines with respect to a spacially fixed sensing axis will vary with lateral displacement of the belt. The targets may assume a variety of specific patterns and the invention is applicable to single and multi-pass image exposure systems as well as to both modulated laser and light emitting diode types of exposure devices.

Abstract: An objective lens actuator for an optical storage drive includes a cross-sectionally L-shaped torsion plate spring which is fixed at its central portion to an objective lens holder and at its opposite ends to free ends of a pair of parallel spaced, cantilevered plate springs. The torsion plate spring is caused to twist to displace the objective lens holder and an objective lens mounted thereon in the tracking direction. The parallel spaced plate springs are caused to bend to displace the objective lens holder and the objective lens in the focusing direction.

Abstract: A method and apparatus for editing video cassettes. The video cassette editor can be used to move a video cassette to a particular position on the tape relative to a reference point as a function of tape length expressed in units of time. The video tape editor is also capable of calculating recording speed switchover points for maximizing the recording time in standard play mode and thereby increasing the quality of the video image for the maximum amount of time.

Abstract: An apparatus for processing an interlaced video signal having (2n+1) horizontal scanning lines (n: an integer) for one frame, which consists of two fields, is provided with a memory capable of storing at least an (n+1) horizontal scanning line portion of the video signal. The apparatus is arranged to reset the reading address of the memory alternately at an interval of n horizontal scanning periods and at an interval of (n+1) horizontal scanning periods and to reset the writing address of the memory in response to the front edge of a vertical synchronizing signal included in the input video signal.

Abstract: An optical head device having an optical system provided with at least a light source, a shaping prism, a diffracting element and a photodetector. The light source emits light whose cross-sectional intensity distribution has an elliptic shape. The shaping prism directs the light to a recording medium after shaping the intensity distribution thereof into a circular shape. The diffracting element has diffracting regions formed by at least one division line parallel to a reference direction. The light reflected from the recording medium forms an elliptic bright portion on the diffracting element. The photodetector is divided by a plurality of division lines, at least one of which is parallel to the reference direction. When there is no focus error, the diffracting element diffracts the reflected light so as to converge it on the division line substantially parallel to the reference direction in the photodetector.

Abstract: A track access control method and apparatus for an optical disk apparatus are disclosed. Where a locus of movement of an object lens through which a write beam and a read beam are projected onto an optical disk upon track accessing is offset from a straight line which passes the center of the optical disk, the positional relationship of the read beam and the write beam is controlled relatively in accordance with a track position so that, at any track position, the read beam and the write beam can be positioned on the same track.

Abstract: In the optical recording element of the invention, alignments of long thin pits inclined in various directions with respect to the track direction are formed on the tracks and information is recorded therein according to the different inclines of the pits, thereby performing higher-density and larger-volume recording without reducing the spacing between each pit and the track pitch. The invention also discloses an optical data retrieval system for use with the above optical recording element, which scans the pit alignments with a laser beam spot, detects the inclines of the pits by obtaining the distribution of the intensity of reflected light which is caused by light diffraction at the pits, and plays back information in accordance with the inclines. Therefore, not only can the substantially same structure as that of a standard type optical data retrieval system be applied to the invention without making any complicated change, but also cross-talk is less likely to be produced in the read out signals.

Abstract: A disc playback apparatus for reproducing data from a disc having digital data including at least image data or computer data recorded sequentially thereon includes: a spindle motor for rotating the disc; a pick-up assembly for reading and outputting data from the disc, as an electrical signal; waveshaping circuit for shaping the electrical signal into a pulse signal; a clock extracting circuit for extracting a playback clock signal from the pulse signal; a reference clock generating circuit controlled by a reference clock control circuit, for continuously varying and outputting a frequency of the reference clock signal; and a switching circuit which is switched on and off, the reference clock control circuit increasing the frequency of the reference clock signal when the switching circuit is switched on, and decreasing it when the switching circuit is switched off; a rotation servo circuit for controlling the spindle motor so that the frequency of the playback clock signal is consistent with the frequency of

Abstract: A method for generating a record information composed of a main information having a plurality of formats and a subsidiary information associated with said main information, is disclosed. A discriminative information for discriminating the formats of the main information is arrayed in a synchronizing part of the subsidiary information, and the encoding operation is controlled as a function of the discriminative information to generate the record information. The discriminative information is transmitted to an encoding system within the extent of the data format to enable encoding in accordance with the formats and under maintenance of operational synchronization.

Abstract: A data processing apparatus includes a light source and an objective lens for radiating first and second light beams on a recording medium having a plurality of data and trucking tracks alternately formed and parallel to each other, photodetectors for detecting the tracking error signal from a beam obtained by reflection of the second light beam by the medium, a switching circuit for selectively supplying the tracking error signal to an actuator, a circuit for supplying a moving signal to the actuator to move the first and second light beams, respectively, to a data track different from one data track and a tracking different from one tracking track, and a control unit for monitoring the tracking error signal, for switching the switching circuit to supply the tracking error signal to the actuator in a tracking mode in which a data track is traced with the first light beam, and for switching the switching circuit not to supply the tracking error signal to the actuator in a moving mode for moving the first ligh

Abstract: A disc drive control device maintains power to its circuits after a manual power source switch is opened for a time sufficient to assure that the read/write head of a hard disc drive is moved to its shipping zone. This is accomplished with a bypass device for maintaining power to the hard disc drive until the head is properly stowed in its shipping position after the operator turns off the power switch. Further, a detecting circuit prevents the disc drive from hanging up when the operator turns power on again before the head movement is completed. A timer turns off the power bypass device a short time after the power source switch is turned off, if, for any reason, the power bypass fails to be shut down as a normal result of the completed movement of the read/write head to the shipping position.