Abstract: In a magnetic disk drive of the type using data erase portions as address marks, an address mark detection system has an address mark detecting circuit and a read data masking circuit. The detecting circuit, monitoring a read data signal, becomes active on detecting a data erase portion whose duration is shorter than a predetermined period of time for address mark detection. The detecting circuit is cleared on detecting a data input. The masking circuit, receiving the read data signal, masks any suitable number of read data pulses input immediately after the detecting circuit has been cleared. As a result, even when noise is introduced in the data erase portion, the system prevents the resulting false read data pulses from being output.

Abstract: A digital servo control with improved control accuracy, in which the arithmetical mean of a sequential series of n data words is used as a basis for the nominal value for a NOMINAL/ACTUAL value comparison to derive a setting signal. Depending on the value of the arithmetical mean, also intermediate values of adjacent quantization stages may thus be included and taken into consideration for control purposes.

Abstract: An apparatus and method for recording servo information on a data storage disk disposed within a enclosed data storage system housing. A small access aperture is provided on the housing proximate the pivot axis of a rotatably mounted actuator which permits access to the actuator through the housing. A unique coupling apparatus is installed on or, alternatively, fashioned as an integral part of the actuator to facilitate engagement with a precision pivot assembly of a servo writer at a plurality of engagement locations around the actuator pivot axis. Undesirable residual positional movement of the actuator and transducers during the servo writing procedure associated with shifting or settling of bearings disposed in a bearing cartridge of the actuator rotation assembly is significantly reduced or virtually eliminated by the equal distribution and passivation of torquing forces around the actuator pivot axis.

Abstract: A forced recording medium cartridge unloading system for use with a library apparatus which is operatively connected to a plurality of host computers. Interposed between the host computers and the library apparatus is a library controller that supervises and controls the library apparatus. The library controller issues a forced recording medium cartridge unloading command in response to a key input or to a request from any one of the host computers. An accessor of the library apparatus upon receipt of the forced unloading command from the library controller in turn issues a forced recording medium cartridge unloading command to a recording medium drive unit that writes and reads data to and from the recording medium cartridge loaded therein. This causes the recording medium drive unit forcibly to unload the recording medium cartridge left loaded inadvertently therein.

Abstract: A method and apparatus are provided for maintaining file readback performance compensating for readback errors caused by head/disk interaction used with a data detection channel in a direct access storage device. A readback signal is sensed from at least one disk surface and a data channel error rate is detected responsive to the readback signal. The detected data channel error rate is compared with a first predetermined threshold value and a gain of a phase lock loop (PLL) in the peak data detection channel is optimized responsive to an identified data channel error rate with a first predetermined threshold value. The PLL gain is adjusted until a lowest error rate is detected. A failure warning for the direct access storage device is provided to a user when the detected PLL gain is greater than a predefined loop gain value.

Abstract: A magnetic recording and reproducing apparatus records a signal on a recording track of a magnetic recording medium in a recording mode and reproduces the signal from the recording track of the magnetic recording medium in a reproducing mode.

Abstract: Disclosed are a partial-response record signal regenerating method of and an apparatus for regenerating a record signal of a data area which is read from a storage disc by use of an equalizing circuit after training a circuit constant of said equalizing circuit with a training signal of the record signal read from the storage disc. The record signal regenerating method comprises: a Viterbi decode step of Viterbi-decoding an output into which the record signal is equalized by the equalizing circuit; a decode step of converting an m-bit output which is Viterbi-decoded into n-bits (m>n); and a synchronism detecting step of detecting the training signal from the m-bit output which is Viterbi-decoded and indicating a start of decoding the record signal of the data area.

Abstract: A recording and/or reproducing apparatus in which an access time required when a tape cassette is exchanged can be reduced so that, while one tape cassette is in the timer-activated operation mode, the ordinary operation is carried out by another tape cassette. At least two tape cassette insertion and/or eject openings (4A), (4B) are formed through a single panel (2). Further, this recording and/or reproducing apparatus includes a mechanical deck (5) which records and/or reproduces tape cassettes (3A), (3B) inserted from these tape cassette insertion and/or eject openings (4A), (4B). The tape cassettes (3A), (3B) can be loaded onto at least two trays (7A), (7B).

Abstract: A method and apparatus are provided for servo demodulation in a direct access storage device. A readback signal is sensed from at least one disk surface and locations of positive and negative peaks in the sensed readback signal are detected for providing a detected peak signal. A square wave signal having a period variable with distance between detected locations of positive and negative peaks is generated using the detected peak signal and applied to a servo demodulator in the direct access storage device.

Abstract: A method of controlling start-up of a sensorless spindle motor used in a disk apparatus reduces time spent on start-up of a spindle motor with high reliability. The motor is used for rotating a disk on which information is recorded, and no sensor is provided in the motor for sensing an angular position of a rotor relative to a stator of the motor. The motor is operated at a steady rotational speed and is stopped by supplying a stop command. An aligning operation is performed immediately after the motor is stopped. The aligning operation is performed to rotate the rotor to a predetermined angular position relative to the stator of said motor. The motor is operated at a steady speed by a synchronization control when operation of the motor is started by supplying a start command.

Abstract: An optical information recording/reproducing apparatus records information on and/or reproduces information from an optical recording medium and detects a focal error based on a reflected light beam from the optical recording medium. The apparatus includes a composite prism which deflects a part of the reflected light beam to at least two positions excluding a central part of the reflected light beam, and a photodetector device having a plurality of photodetectors which respectively detect the deflected parts of the reflected light beam and output detection outputs. The focal error is detected based on the detection outputs of the photodetector device.

Abstract: A digital information restoring device is arranged to detect time between level transition points of a digital signal which indicates digital information by means of variations in its period, output the resultant period data, calculate an average value of at least two period data among the output period data, and compare the average value with the aforesaid period data, and restore the digital information. The digital information restoring device is, therefore, capable of restoring the digital information at a high speed without using a high-speed PLL circuit or the like. The digital information restoring device may also be arranged to perform time-axis expansion of only part of the received period data, and input the resultant period data to a computing circuit to restore the digital information.

Abstract: An HDD, to which servo data is written, is fixed on a base. As an upper base moves, a both-end supporting mechanism provided on the upper base approaches a rotation shaft which supports a disk. When the both-end supporting mechanism is brought into full contact with the tip portion of the free end of the rotation shaft, a process of writing servo data is carried out on the disk. While writing the servo data, the rotation shaft is maintained in the both-end supported state, and therefore a non-repeatable vibration of the rotation shaft caused by a rotation of a spindle motor is suppressed. After the servo data writing process, the both-end supporting mechanism is withdrawn from the rotation shaft as the upper base moves.

Abstract: A multi-track servo recording head includes a multi-tip write core for simultaneously writing a plurality of tracking signals on magnetic storage media. The magnetic recording head may include an optical edge sensor and a magnetic edge sensor for sensing the position of the recording head relative to the edge of the storage media. Additionally, a read core is provided to detect the longitudinal position of the storage media relative to the recording head during media transport.

Abstract: A motor speed control device includes a frequency signal generating circuit for generating a frequency signal proportional to a rotation frequency of a motor, a frequency measuring circuit for measuring a frequency of the frequency signal, a speed error signal extracting circuit for extracting a speed error signal by operation comparing the frequency of the frequency signal with a predetermined control target period, a filter circuit for eliminating rotation frequency components of the motor contained in the frequency signal or the speed error signal and harmonic components thereof to output another speed error signal, and a speed error signal feedback circuit for feeding-back negatively the other speed error signal from the filter circuit to the motor, in which owing to the fact that the filter circuit has predetermined transfer functions, it suppresses non-uniform components contained in the speed error signal and the phase error signal due to the frequency signal (DFG signal) proportional to the rotation s

Abstract: A technique for writing a servo-pattern on a storage medium located in a recording device having an internal recording head. A timing pattern is generated on the storage medium with the internal recording head and a radial positioning value is determined in order to radially position the internal recording head. The servo-pattern is written using the internal recording head at locations determined by the timing pattern and the radial positioning value.

Abstract: A magnetic or optical disc device which can correctly follow the eccentricity of an eccentrically chucked disk and Which can immediately follow the eccentricity of the new disk face when there is a changeover of the disc being accessed operates with a disc having data tracks provided with uniformly spaced clock marks for providing a timing standard and includes a reproduction circuit for reproducing data from the disc, a clock sampling circuit for extracting a first clock signal output by the reproduciton circuit, an eccentricity magnitude memory section for storing a signal corresponding to the eccentricity of the data tracks with respect to the axis of rotation of the disc; a clock correction section.

Abstract: An automatic clock signal phase adjusting circuit for use with a digital magnetic recording and reproducing apparatus adopting a partial response class IV coding method. The automatic clock signal phase adjusting circuit comprises: a pattern detection circuit for detecting at least one of patterns "1, 0, -1" and "-1, 0, 1" from a reproduced signal; a level detection circuit for detecting the levels of the reproduced signal in effect when the pattern detection circuit detects 0's; a clock reproduction circuit for reproducing a clock signal from the reproduced signal; and a phase adjustment circuit for adjusting the phase of the clock signal reproduced by the clock reproduction circuit based on the output signal from the level detection circuit.

Abstract: Digital video tape recorder for recording and reproducing digital video and audio data in respective tracks in a predetermined format on a record medium. The predetermined format having respective video, audio and subcode areas with each area having a number of sync blocks comprised of a data area in which video, audio and system data, respectively, are recorded. These areas are preceded by a fixed area in which sync block identifying information is recorded. The data area of the subcode area is formed of data packs having a common pack structure and system data provides for automatic control during reproduction and for identifying the recorded digital video and audio data.

Abstract: A demodulator for a servo control system receives a servo signal that is produced from reading a servo pattern that comprises a repeating sequence of trigonometric-compensated, phase-encoded magnetic flux transitions that extend continuously across the width of a servo track and includes a burst cosine phase detector that samples the amplitude of the servo signal at regular intervals and produces burst sample data, from which the demodulator produces a position error signal that is a substantially linear function of the servo head position relative to the servo track width. Because a plurality of amplitude samples is taken from each cycle of the servo signal, an increased signal-to-noise ratio can be obtained for the servo signal. The superior signal characteristics permit smaller and less complex demodulator elements to be used, thereby reducing the overall servo control system complexity.