Abstract: A drum servo circuit for a magnetic recording and/or reproducing apparatus uses a 30 Hz or 60 Hz oscillator circuit (counter), and a trapezoidal wave signal (or a sampling pulse signal) is produced by selectively using threshold values set in the oscillator circuit depending on the play mode, so as to eliminate the need to externally couple a plurality of variable resistors to a monostable multivibrator. A drum motor which drives a rotary drum is controlled responsive to a phase error signal which is obtained by comparing the phase of the trapezoidal wave signal (or the sampling pulse signal) and the phase of a rotation detection signal which is obtained by detecting the rotation of the drum motor.

Abstract: Improvements are realized in magnetic disc drives in minimizing servo gain variations from one head to another and in differing track offset positions by providing servo code patterns and methods of fabricating such patterns in which magnetic heads of differing widths overlap the same amount of servo code and in which servo gain variations in track offset positions are minimized by maintaining servo code overlap by the magnetic heads relatively constant up to substantially one-half track offsets of magnetic head.

Abstract: A disk drive control system including servo sectors written on a disk, with each sector containing three sets of marker pulses arranged so that three adjacent marker pulses from each of the sets spans two tracks. The pulses each comprise high frequency sinusoidal signals. Servo control depends upon the pulse amplitudes sensed by the read/write head while traversing a servo sector. The system includes an amplifier to rectify and amplify the high frequency signals, a sample-and-hold circuit to hold at least three value representative of the amplified high frequency signals, and synchronizing means to synchronize the sample-and-hold circuit such that the first value sampled and held is representative of the amplitude of the first pulse read in a servo sector, the second value sampled and held is representative of the amplitude of the second pulse read in the servo sector, and so forth. A multiplexing circuit provides multiplexed signals sequentially representative of values sampled.

Abstract: An apparatus for recording and/or reproducing a digital signal on a recording medium having at least a program start signal and program information recorded thereon, further records an identifying code signal indicating the start of unnecessary information on the recording medium during a predetermined time period, and, in a playback mode, when such identifying code signal is detected, the recording medium is transported at high speed and, when a program start signal is next detected, the recording medium is again transported at a normal speed.

Abstract: A magnetic recording-reproducing device for recording a signal on a magnetic tape and/or reading out a signal from the magnetic tape to reproduce the same while running the magnetic tape in contact with a rotary drum having at least two heads, which is characterized in that it comprises a frequency generator for generating a pulse train having a frequency proportional to the rotating speed of the rotary drum, a pulse generating unit for generating a pulse indicating the direction/position of rotation of each head each time the rotary drum rotates a certain angle of rotation, a delay circuit for delaying the phase of the pulse supplied from the pulse generating unit, and a gate circuit for computing the logical product of the pulse supplied from the delay circuit and the pulse supplied from the frequency generator, wherein the pulse supplied from the gate circuit is treated as a pulse indicating a true head position, whereby the true head position pulse can be generated electrically, easily and accurately when

Abstract: The apparatus is for recording and reading binary information on a magnetic disc (14) of rigid type, with a plurality of concentric recording tracks. Each track comprises a useful zone for storing binary information and a function zone in which information which is used for correct positioning of the head with respect to the central axis of the track is pre-recorded. Moreover, in the function zone of a predetermined track, information identifying this track as a reference track is also pre-recorded. A stepping motor (22) is adapted to position the magnetic recording and reading heads with respect to the tracks of the disc and is driven by a circuit which comprises a voltage source (51) and a voltage boosting circuit (53) which supplies the stepping motor (22) with a voltage (PA) higher than that (PW) supplied by the voltage source (51) during the presence of a command signal (RC) which is emitted by a control unit (15) during the time required to shift the heads from an existing position to a new position.

Abstract: An improved servo positioning system for a Winchester disk drive system is disclosed. A plurality of concentric servo tracks are provided on the surface of one disk. Each track is comprised of an equal number of frames of a preterminded length. Four basic frame patterns are utilized. In addition, a frame may also have a code bit in a predetermined position, in order to define the frame as a "one" or "zero" frame. The servo data is read by a dedicated servo head, digitized and fed to a logic array which receives as its only other input an 8 megahertz clock signal. The logic array detects the sync signals present in each frame and generates index, guardband and no sync signals therefrom. In addition, a plurality of windows, each corresponding to a predetermined portion of each frame, is generated. Those window signals are utilized to control a window control circuit which sequentially enables four similar peak dectors, one for each window.

Abstract: Disclosed is a method for recording a record that emulates a first recording format, which includes a track reference point, such as an index field, used for determining a position of a record on a track according to the first recording format, on a moving storage device operating according to a second recording format which also includes a track reference point. The invention comprises the steps, responsive to location information generated according to the first recording formats, of:(1) determining an original angular position of a record according to the first recording format;(2) calculating in response to the original angular position and a parameter a preferred angular position for the record according to the second recording format;(3) determining an actual angular position of the record recorded according to the second recording format; and(4) recording an extension of the record to compensate for the difference between the preferred angular position and the actual angular position.

Abstract: A digital servo control system for a data recording disk file receives as input a digital head position error signal (PES) and a digital signal corresponding to the head actuator input signal, and outputs a digital control signal. The control signal is integrated and amplified to provide the input signal to the actuator. The control signal is calculated from estimated values of absolute head position, head velocity and the equivalent actuator input signal required to compensate for constant or very low frequency bias forces. The estimated values are functions of respective predicted values, which in turn are functions of, among other things, constants representing the digital sampling time and physical parameters of the actuator. The updating of the estimated values from the respective predicted values is made with the use of an error term, which is the error between the measured absolute head position and the predicted absolute head position.

Abstract: The disclosed information signal reproducing apparatus reproduces information signals from a recording medium with a number or tracks. Four pilots signals having different frequencies from one another are recorded successively on the tracks along with information signals. A reproducing element only traces alternate ones of the recording tracks. A generator produces a signal having a prescribed frequency. A signal processing circuit forms a tracking control signal for a reproducing element from the prescribed frequency signal obtained from the generator and the pilot signals reproducing by the reproducing element, and a control circuit controls the tracking of the reproducing element based on the tracking control signal.

Abstract: For exact positioning of a magnetic head to various tracks of a magnetic tape by use of a stepping motor, a plurality of motor control steps required in order to position the magnetic head to the various tracks proceeding from a reference position are identified. For the compensation of manufacturing tolerances, individual positional values are identified for every magnetic tape recorder. These positional values indicate a precise position of the magnetic head on the center of the respective track. The positional values are stored in a read-only memory, or are formed by addition of stored standard values and correction values stored in a read-only memory.

Abstract: A recording apparatus for a video signal in which first and second heads for recording and reproducing are attached through electrostrictive elements to a rotary drum with an angular spacing of substantially 180.degree. therebetween. When a video signal is recorded, a pilot signal recorded by the first head over a predetermined interval is reproduced by the second head while a pilot signal recorded by the second head and spaced apart by a predetermined number of recording tracks is reproduced by the first head. Reproduced levels of the pilot signals are compared so as to control a drive voltage for the electrostrictive elements and thus to adjust a step difference between the first and second heads in the recording mode.

Abstract: A tracking apparatus for a signal reproducing apparatus makes use of a rotating magnetic recording medium, especially when such apparatus reproduces information signals recorded on the medium, such as video signals. The tracking apparatus includes a compensation circuit capable of compensating for the envelope level of the signals sensed by the playback head, so that the dynamic range for which the envelope signal is quantized may be narrower, or the quantum level steps may be smaller, and hence the resolution thereof may be enhanced correspondingly.

Abstract: A high velocity seek deceleration technique is disclosed for seek operations of disk drives wherein measured time per track is compared to a predetermined time per track in a memory as indexed by number of tracks to end of seek determines an error value which adjusts a deceleration amplifier. The gain of digital output to the amplifier is adjusted depending on the number of tracks to end of seek, the higher the number, the higher the gain. Further, a variable bandwidth filter is employed to increase bandwidth as velocity decreases.

Abstract: Tape flutter, caused by head-to-tape stick-slip action, is suppressed in tape transport apparatus of the turnaround type having a single, speed-regulated capstan for metering magnetic tape into and out of a magnetic transducer station. To that end, a low-inertia motor, coupled to a turnaround roller, includes a tachometer for monitoring the instantaneous speed of the roller, and thereby the speed of the capstan tape loop. A phase lock loop, coupled to the tachometer, produces a composite signal including a nominal component corresponding to a desired tape speed, and an error component corresponding to tape flutter in the capstan loop. A bandpass filter, coupling the output of the phase lock loop and the motor, causes the motor to adjust the speed of the turnaround roller in phase opposition to the error component, to thereby suppress flutter in the capstan tape loop.

Abstract: A reference track is recorded in a longitudinal direction on a recording medium. During recording of an information signal along parallel tracks on the medium a deviation of the reference track in a transverse direction from its nominal position with respect to the medium transport is detected by one or more sensor heads mounted in a fixed relationship with respect to the medium transport. A positionably mounted data head is moved in transverse direction in accordance with the sense and magnitude of the detected deviation, thereby maintaining the data head in a known geometric relationship with the reference track during the recording process. During playback the same reference track may be utilized to follow the thusly recorded parallel tracks.

Abstract: A method and apparatus for synchronizing a plurality of tape recording and playback machines is described. A synchronizing device for each tape machine to be synchronized is provided. The synchronizing devices are coupled to each other via a communications channel including a serial port for transmitting control information and an additional conductor for transmitting master timing reference pulses. A synchronizing device is chosen as a master device. The master device transmits master timing reference pulses via the communications channel to the remaining tape machines, the pulses indicating the start of each frame on the master tape. Each of the remaining tape machines is a slave to the master. Frame numbers for selected frames on the master tape are transmitted on the serial port to the slave tape machines, but only on an infrequent basis, i.e., a frame number is not transmitted for each frame.

Abstract: A magnetic disc recording and reproducing apparatus for magnetic discs wherein the gap of the recording and reproducing head is mounted parallel and ahead of a radial through the disc so as to record and reproduce a track and a pair of erasing heads are integrally formed with said recording and reproducing head and have gaps which are parallel and behind the same radial through disc so as to erase the outer edges of the track. The gap of the recording and reproducing head is symmetrically mounted with the erasing head gaps.

Abstract: An apparatus and method are disclosed for positioning magnetic heads relative to the recording tracks of a recording medium such as a floppy disk having circular, concentric recording tracks formed thereon. The magnetic heads are mounted on a head carriage, and the head carriage is moved, in response to received command pulses, so that the heads are moved linearly, by step increments, along a radius of the floppy disk. The heads are thereby moved across the spaced tracks on the disk, with each incremental movement of the heads being a distance less than the distance between the tracks, and being, for example, one-half or one-fourth of the total distance between tracks. Acoustic noise due to head movement is minimized by moving the heads by increments less than the distance between the tracks, with such movement avoiding exciting the resonances of the head moving apparatus.

Abstract: A magnetic recording and reproducing apparatus includes a support assembly and a plurality of magnetic heads supported by the support assembly for recording audio information signals on and reproducing previously recorded audio information signals from a magnetic disc. The magnetic heads are positioned relative to the magnetic disc by a magnetic head moving arrangement which is coupled to engage the disc so as to automatically eject the disc from the magnetic heads.