Abstract: In an electronically commutated head drum motor in combination with a motor control circuit, commutation control and tacho signals are generated from the commutation of winding strands. One of the winding strands is used for the phase detection of the read/write heads arranged on the perimeter of the rotating head drum. A commutation signal is derived from the commutation of this winding strand and the commutation signal is set in relation to the reference signal of a signal track to be recorded or scanned.

Abstract: A circuit for generating a clock of a predetermined frequency in folllowing-up relation to an input video signal, comprising a PLL circuit including a phase comparison circuit for comparing the phase of a synchronizing signal of the video signal with the phase of a feedback clock corresponding to the clock, and a control circuit for causing the feedback clock in the PLL circuit to be synchronized with the synchronizing signal.

Abstract: A method for testing slider/disk contact in a disk drive is described. The disk drive comprises a rotating disk having tracks and a head mounted by an actuator for selective positioning of the head over any one of the tracks of the disk. The head includes a slider. The method comprises the steps of positioning the head at each of a preselected set of tracks, while at each one of the preselected set of tracks, rotating the disk of the disk drive at a preselected rotational velocity and using the head of the disk drive, at each track, to write a signal having a substantially uniform pattern on the disk as it rotates. Thereafter, rotating the disk at a fixed preselected rotational velocity, and while rotating at the fixed preselected rotational velocity, using the head to read back the signals written at each one of the preselected set of tracks. The read back signals are used to determine rotational velocities at which slider/disk contact occurs.

Abstract: In a magnetic recording/playback apparatus for recording and playing back a digital video signal on a helical track of a magnetic tape using two or more rotary heads, the playback image at the time of high-speed playback is improved by setting the tape travel speed at the time of high-speed playback at an even multiple of a normal playback speed. Further, a tracking phase is offset by one half the track pitch with respect to the tracking during normal speed playback. Alternatively, essential information of the information having been high-efficiency coded is recorded in the central part, and near the ends of the tracks, while high-precision information is recorded in intermediate parts intermediate between the central part and the parts near the ends. Still alternatively, the video data of one of the consecutive fields is recorded in the central part of the tracks and the video data of the other of the consecutive fields is recorded near the ends of the tracks.

Abstract: A helical scanning magnetic recording apparatus utilizing Azimuth recording technology includes a reading head and a writing head which are arranged with a predetermined dimensional relationship. When the recording to a recording tape, the reading head and the writing head simultaneously record a first track and a second track beside the first track. Since the writing head is located on the upper stream side than the reading head, the writing head can be tracked on the next track position when the, reading head is placed over the first and second tracks such that the reading head reproduces the first and second tracking signals having the same amplitude.

Abstract: A magnetic disk apparatus is disclosed wherein the apparatus comprises a magnetic disk, magnetic heads for recording and reproducing information to and from the magnetic disk, a disk driving device for driving the magnetic disk, head driving device for driving the magnetic heads, a mechanical portion driving circuit for operating the disk driving device and the head driving device, a logical operation device for exchanging signals between the magnetic heads and the mechanical portion driving circuit, a first box for containing at least the magnetic disk, the magnetic heads, the disk driving device, and the head driving device, and a second box, detachably connected to the first box, for containing at least the logical operation device, wherein signals are exchanged between the first box and the second box. The first box and the second box are electrically connected and the second box contains at least the logical operation circuit.

Abstract: An apparatus for movably mounting a full erase head for use in a video cassette recorder includes a solenoid positioned at one side of a deck in the video cassette recorder, a relay lever supported by a pivot secured to the deck in such a way that it is permitted to turn about the pivot by the solenoid, and an interlocking lever for mounting the full erase head, the interlocking lever being supported by a hinge fixed to the deck in such a way that it is allowed to swing about the hinge, depending on the movement of the relay lever, whereby the full erase head is allowed to come into contact with the tape even if the video cassette recorder may be in a fast forward/rewind mode.

Abstract: Methods of calibrating a helical scan recorder include transporting a storage media past a drum at a controlled linear velocity and recording tracks on the media using a write head. During a read-after-write operation, servo signals recorded on the track; are read. The servo signals from the tracks are used to determine an axial offset variance of the write head and a read head on the drum. In one mode, calibration is achieved for a first helical scan recorder which does not have a capstan, by installing a drum of the recorder in a second helical scan recorder, using the second recorder to record servo signals on two tracks, reading the servo signals from those two tracks, second recorder, using the servo signals to determine axial offset variance, and storing a value indicative of axial offset variance in a memory of the first recorder. The axial offset variance is used in a write splice operation and, in one mode, to determine linear velocity of the media.

Abstract: A Video Tape Recorder (VTR) with a liquid crystal display (LCD) projector free from a radiating blower is disclosed. The VTR with LCD projector includes a plurality of fins positioned on a top surface of a rotary head drum for generating air currents during rotation of a rotary head drum of a VTR part. A polarizing plate of the LCD projector part is cooled by the air currents generated by the fins. The VTR with LCD projector achieves compactness and reduction of cost, in keeping with the recent market trend.

Abstract: A method of positioning the read/write head onto a desired data track in a multi-track recorder/player utilizes a plurality of registration stripes to find the central axis of a data track. In one embodiment, each registration stripe has associated with it a recorded identification pattern or tone which may be sensed and used for identification purposes. Then, based upon the read amplitude output of the read head, the appropriate edge of a registration stripe may be detected and, from there, the read/write head moved directly onto the desired data track without any subsequent open-loop movement. In an alternative embodiment, multiple edges are sensed and used in a calculation to determine the lateral displacement associated with the longitudinal centerline of a desired data track.

Abstract: A motor control circuit generates a signal representing a rotation frequency of a motor. It produces a motor speed error signal based on the rotation frequency. The error signal is changed by a speed gain circuit and supplied to the motor driving circuit through a filter. The filter is for preventing an oscillation in a servo loop. When the motor speed is out of a predetermined range, a gain of the speed error signal is reduced and the filter is disabled.

Abstract: This invention relates to automatic tracking devices of digital VCRs which is provided to have a capability of precise control of the tracking by detecting rate of error due to variation of tracking of a rotating head.

Abstract: A sensing current adjusting zone is formed in the outermost or innermost periphery of a magnetic disk and reference signals are recorded in a recording width corresponding to the width of a plurality of tracks in the sensing current adjusting zone so that the phases of the reference signals are the same and the radially adjacent reference signals overlap each other. When adjusting the sensing current, an MR head is moved forcibly into the sensing current adjusting zone to reproduce the reference signal and the sensing current is adjusted so that the difference between the respective absolute values of the plus peak and the minus peak of the reproduced reference signal is reduced to the least extent.

Abstract: A video cassette recorder (VCR) is disclosed which is capable of displaying the video being erased during a recording operation. Thus, during a recording operation the user is able to monitor the video being erased, so as to stop recording if the VCR has reached a video the user wishes to preserve. The VCR is capable to display the video being erased during a recording operation by doubling the rotational speed of the head cylinder during a recording operation. Since the rotational speed is doubled, half of the time period is used for reading and half for recording. The VCR includes a decompressing circuit to restore the video read during the double speed rotation of the head cylinder, and also includes a compressor to compressed the externally supplied video so as to record that signal at double the normal rotational speed.

Abstract: In a video tape recorder capable of recording information for a long time, first and second rotary heads are angularly spaced by 180.degree. and are arranged without a step between their respective planes of rotation. In a frame recording operation, an odd field of a frame is recorded by the first head in a first track on the tape while the latter is in a stationary condition and an even field of the same frame is stored in a field memory, whereupon, the tape is intermittently driven a distance corresponding to the track pitch and then, while the tape is again in its stationary condition, the stored even field is read from the memory and recorded by the second head in a second track adjacent the first track.

Abstract: A sliding mode controller for controlling a read/write head actuator in a magnetic disk drive storage system wherein a voice coil motor connected to the actuator operates to adjust the position of the read/write head over a selected data track recorded on a magnetic medium. The sliding mode controller comprises a technique for reducing chatter associated with the inherent operation of such a controller--rapid switching between gains to force the observable phase states to follow a predetermined phase state trajectory. While tracking the centerline of a selected track, the sliding mode controller generates a motor control command by multiplying an actuator position error and an actuator position error velocity by respective switching gains. When seeking to a new track, the controller reduces switching noise by disabling the actuator position error and generating the motor control signal responsive to the actuator position error velocity alone.

Abstract: Circuit for generating a write disable signal in response to an applied shock force. Angular displacements which indicate an excessive shock force are detected, and signal processed to determine whether or not a displacement will result from the shock force exceeding a threshold level. Low frequency displacements are de-emphasized, while higher frequency displacements in a passband of interest are integrated to obtain a displacement function. The displacement function is compared in a threshold detector with a reference threshold displacement level. Displacements which exceed the established threshold displacement will generate a write disable signal.

Abstract: Determining a micro-jog parameter in a disk drive that employs a magneto-resistive (MR) transducer head assembly and a partial response (PRML) detector includes improved accuracy in measuring on-track signal strength by use of a matched filter technique. The matched filter includes circuitry for emulating a partial response signal expected to be produced by a selected test bit pattern prerecorded on the selected track. The matched filtering technique provides improved accuracy in measuring the detected signal strength as it provides an extremely narrow digital filter focused on the test bit pattern frequency. Improved determination of the micro-jog distance further includes measuring interference from adjacent tracks, the best error rate being achieved at micro-jog positions intermediate the maximum on-track signal strength and the minimum off-track interference. A novel digital detector for accurately measuring adjacent track interference also is disclosed.

Abstract: A method of, and an apparatus for, the two-channel recording/playing back of signals in a VCR, wherein video data is divided into a signal with two channels to be recorded, so that HDTV signals can be recorded on a general S-VHS tape and played back therefrom. The apparatus includes: record system means for interleaving inputted data to divide it into two channels by adding dummy blocks and synchronizing blocks to the data at intervals of every two frames so as to record the data in two channels; playback system means for detecting data; and, synchronizing signal means for removing the dummy blocks and synchronizing blocks, based on the synchronizing signal, so as to format the data; means for combining and de-interleaving data of the two channels, and means for error-correcting and decoding the two channels.

Abstract: In a helical scan system for recording information on a storage media in a series of helical tracks, servo information written on the tracks is used to control linear velocity of the media during a write operation. Helical scan system includes a rotating drum upon which write heads and read heads circumferentially are mounted. The write heads and the read heads are positioned on the drum so that during a drum revolution a read head reads servo information recorded on a track at least 1.5 track pitches upstream from the most recently recorded track. A servo controller analyzes, during the recording operation, servo information read back by the read head subsequent to recording thereof by write head. Servo controller uses the servo information read by the read head to generate a signal for application to a motor for controlling linear velocity of the media during the write operation.