Abstract: Data reliability testing for a magnetic tape drive is conducted separately for the channels of a magnetic tape drive which write and read tracks of a multiple track magnetic tape. Memory stores testing data representing data separately written to tracks of a multiple track magnetic tape; each of a plurality of read channels reads data sensed by a tape head from a separate track of a magnetic tape; and error processing logic detects differences between data from each of a plurality of the read channels, and stored testing data of the memory representing data written to the same separate tracks.

Abstract: Magnetic tape read channel signal values are developed employing intermediate bits of the path memory of a PRML Viterbi detector. Identification logic identifies a most likely path memory state of the PRML Viterbi detector from the path metrics of the PRML Viterbi detector. An intermediate bit sequence of the identified most likely path memory state is obtained, the intermediate bit sequence extending from an initiation point of the path memory which is intermediate the output and the input of the PRML Viterbi detector. A sample value is determined which corresponds to the obtained intermediate bit sequence.

Abstract: Embodiments of the invention provide a servo information write method that makes it possible to properly locate the last-written servo information even when old servo information is overwritten by new servo information. In one embodiment, a servo track writer controller, which is within a servo track writer, reads a serial number (S/N) from a HDD (step 101), and acquires a magnetic disk drive servo information write count (P-ID) from a manufacturing process host (step 102). The next step (step 103) is then performed to control a positioner and a read/write channel so as to start writing servo information onto a magnetic disk. Servo information is sequentially written until the last track is written into (step 104). When the Nth servo information is to be written, a P-ID (N) is written subsequently to a burst signal (step 105). When the last track is written into in step 104, step 106 is performed to notify the manufacturing process host that the Nth servo information write is performed.

Abstract: An address is reliably demodulated when a phase shift in a wobble signal has been induced by a crosstalk signal from an adjacent track. Address information is modulated by a binary phase modulation scheme and embedded into an optical disk as a wobble signal. A 0-degree phase wobble signal and a 180-degree phase wobble signal are brought out of phase with each other by crosstalk from an adjacent track. An address decoder performs exclusive-OR operation of the wobble signal and a reference clock signal, to thus compute a ratio at which an exclusive-OR result assumes a value of 1 (H) every half period of the reference clock signal. The thus-computed ratio is compared with a threshold ratio. The threshold ratio is usually set to 50%. However, when a phase shift has been caused by crosstalk, a system controller changes the threshold ratio to a ratio of 50% or less.

Abstract: Embodiments of the invention provide a magnetic disk drive and its control method capable of effectively using the unrecordable area which is caused due to the composite magnetic head's gap between the read head and the write head. In one embodiment, a disk drive comprises a composite magnetic head structured in such a manner that during write the write head WH reaches each servo area earlier than the read head RH, and a read write control unit to control the write and read done by the composite magnetic head. On the disk, common servo data SP to be used both during read and during write, write servo data SW to be used during write and read servo data SR to be used during read are recorded in this order in each servo area. During write, the read write control unit starts the write head recording data at the timing when reading write servo data SW from the servo area is completed.

Abstract: A retract control method of an HDD to prevent a head from landing on a disk due to a retract failure and an HDD using the same. The retract control method includes performing a retract operation of retracting a head on the ramp, determining whether the head is normally retracted on the ramp, when it is determined that the head is not normally retracted on the ramp, moving the head to a predetermined zone of a disk, and when the head arrives at the predetermined zone of the disk, parking the head in the predetermined zone of the disk by stopping a spindle motor. Accordingly, even when a retract operation fails, a reliable retract operation can be performed by retrying the retract operation while adjusting one or more retract parameters.

Abstract: A method for identifying adjacent track interference for a head is provided. The method comprises writing a first data track at a predetermined track position; writing a second data track two track positions away from the first data track; and validating the position of the first data track and the second data track. Upon validation the method further comprises writing a third data track between the first data track and the second data track and analyzing a signal profile of at least one of the first data track and the second data track for adjacent track interference.

Abstract: A system comprises a positioning module that positions an actuator arm to read spirals that are prewritten. A frequency measuring module measures a first frequency of sync marks of said spirals. An estimation module calculates a second frequency of said sync marks when said actuator arm moves at a predetermined actuator velocity. A control module calculates an actuator velocity at which said spirals are prewritten based on said first frequency, said second frequency, and said predetermined actuator velocity.

Abstract: An optical pickup apparatus is provided with a dividing element having a plurality of regions. The dividing element is capable of dividing a light flux reflected by the optical disc into a plurality of light fluxes having different outgoing directions. Each region of the dividing element and light receiving parts of a light detector are structured such that when a target information recording layer of the optical disc is brought into focus, a light flux reflected from the target information recording layer is focused on the light receiving parts of the light detector, and a light flux reflected from other information recording layer than the target information recording layer is not irradiated onto the light receiving parts of the light detector.

Abstract: A partial response is utilized to record information on a medium and then regenerate the information from the medium. A regenerating system undergoes equalization including subjecting a regeneration signal from the medium to the convolution of (k?s·D) (where D is one (1) bit delay operator, and k and s are positive integer). Such convolution is performed in the regenerating system so that low-frequency band noises are reduced with an improved error rate. The information is decoded from the equalized signal by use of maximum-likelihood detection.

Abstract: A multilayer recording medium that prevents deterioration of a signal characteristic due to a mirror effect that may occur between recording layers and a method of manufacturing the same, the multilayer recording medium having at least two recording layers, wherein a thickness of at least one spacer layer between adjacent recording layers is different from a thickness of the other spacer layers such that a beam focusing on a recording layer is prevented from focusing on another recording layer corresponding to a mirror layer due to reflection. In the multilayer recording medium, a mirror effect is greatly reduced. In addition, the thickness of only a spacer layer exerting the most significant influence on the mirror effect is changed to prevent the deterioration of signal quality due to the mirror effect, and therefore, the structure of a multilayer recording medium is simplified.

Abstract: An apparatus and method for improving the error rate of track information on a magnetic storage device is disclosed. One embodiment provides a counter for counting the number of writes to a first track on a magnetic storage device. In addition, a re-read and re-write initiator is provided for reading information from a second track adjacent to the first track and re-writing the information read from the second track back to said magnetic storage device when said counter reaches a pre-defined number of writes for the fist track.

Abstract: An optical system is described for scanning optical record carriers of different types. The optical system includes a compensator having a number of optical elements (NPS1, NPS2). The optical elements (NPS1, NPS2) are non-periodic phase structures (NPS) having annular areas separated by steps, forming a non-periodic pattern of optical paths of different lengths. By including these multiple optical elements (NPS 1, NPS2) having NPS surfaces in the lens system of an optical system, it is possible to compensate for the effect of variation of a parameters such as temperature, angle of incidence, polarisation of radiation incident on the system and wavelength of radiation, without causing sensitivity to variation of another such parameter.

Abstract: An amplifying circuit and method are disclosed for amplifying electrical signals, such as electrical signals generated by the read head of a disk drive. The circuit includes a pair of cross-coupled differential amplifier circuits. Each differential amplifier circuit is asymmetric, including two input transistors of different transistor types. For instance, a first of the two input transistors of each differential amplifier circuit may be a bipolar transistor and a second of the two input transistors may be a field effect transistor. By utilizing asymmetric differential amplifier circuits, a relatively wider operating frequency range is obtained.

Abstract: A synchronization system includes a signal generating module that generates a signal comprising modulated waveforms and a timing window generator that generates a timing window. A proportional integral controller (a) divides the timing window into a first half window and a second half window, (b) demodulates the digital signal in the first half window and the second half window, (c) compares an amplitude of demodulated signal in the first half window to an amplitude of demodulated signal in the second half window, (d) calculates a new location for the timing window, and (e) repeats (b), (c), and (d) until the amplitude in the first half window equals the amplitude in the second half window.

Abstract: Embodiments of the present invention provide optimization of read/write channels in a recording system by embedding channel optimization algorithm/procedure into the channels, or a system-on-chip (SOC) where a read/write channel is integrated with a disk drive controller, according to an Embedded Channel Optimization Solution (ECOS).

Abstract: Provided is an apparatus and method of initializing a recording layer used in manufacturing a phase-change optical disk for storing information. The optical disk is initialized using a UV lamp in order to initialize the recording layer of the phase-change optical disk capable of repeatedly writing information, without a separate optical head, whereby it is possible to increase productivity by remarkably reducing an initialization time of the optical disk since a large area is initialized using a UV beam.

Abstract: A recording/reproducing apparatus includes: a magnetic recording medium on which data track patterns are formed in data track pattern regions by a pattern with recording regions and non-recording regions and on which servo patterns are formed in servo pattern regions by the pattern; a recording head that writes signals on the medium; a reproducing head that reads signals written on the medium; and a control unit that controls the writing of signals by the recording head and the reading of signals by the reproducing head and measures a predetermined parameter for at least one of the recording head and the reproducing head by writing and reading measurement signals on the medium.

Abstract: A write head for a magnetic storage system energizes a write coil for a plurality of bit intervals and selectively shutters the magnetic field to alter a magnetic domain of a magnetic storage medium for each bit interval. The position of the shutter may be controlled using a micro-electro mechanical system. Magnetic pole segments provide a loop between the write coil and the magnetic storage medium. Magnetic shielding on the shutter mechanisms controls the reflection of the magnetic fields. In a rewritable magnetic storage system, a first write coil generates a positive magnetic field and a second write coil generates a negative magnetic field. A shutter is associated with each write coil to selectively allow the positive or negative magnetic fields to alter the magnetic domain of the magnetic storage medium. The positive or negative magnetic fields can alter the magnetic domain in a collocated region of the magnetic storage medium to avoid jitter.

Abstract: Embodiments of the present invention provide a magnetic disk drive system in which the write element leads the read element in the tangential direction of rotation of the magnetic disk. In addition, the servo sector information is preferably arranged such that information that is not needed for write operation is placed at the end of the servo sector. In this way, the servo read operation can be terminated sooner and the write operation can initiate sooner after going over the servo sector. The write element in a write operation writes data to the data sector of a track until an end of the data sector before reaching a front end of a servo sector following the end of the data sector. The read element reads information in the servo sector needed for the write operation. The write element starts writing data in a next data sector following the servo sector after the write element reaches the next data sector and after the read element has read all information in the servo sector needed for the write operation.