Abstract: A method to enable servo information to be detected surely and stably even when a time interval between servo sectors is changed due to disk shifting. A time interval TS(i) is calculated according to an internal variable value, which is in proportion to a displacement &Dgr;r(i) of a servo area SF(i) in a radial direction of a subject disk (step S6). The displacement &Dgr;r(i) is calculated from already detected servo information[, thereby]. Thereby, a time interval for detecting servo information is adjusted according to the above described time interval TS(i) (steps S7 and S4). The time interval TS(i) is the time interval between passing of a servo sector in the servo area SF(i) under the head H and passing of a servo sector in the servo area SF(i+1) under the head H.

Abstract: A method and apparatus for Read-After-Write (RAW) verification with error tolerance is disclosed whereby upon read back of data from a medium, the actual read data can be compared to the actual write data, and the number of miscompares between the two can be counted. The severity of the number of miscompares can be determined depending on the Error Control Code (ECC) system used. If the error is correctable by the ECC system, the block need not be re-written to the medium. The invention provides the ability to increase medium capacity and throughput over previous implementations.

Abstract: A method and circuit are disclosed for controlling the write head of a magnetic disk storage device. The circuit includes a pull-up device coupled to a terminal of the write head, a current sink circuit which is coupled to the write head terminal and a bootstrap circuit coupled to the current sink circuit. When reversing the direction of current flow through the write head so that current is drawn from the write head from the write head terminal, the bootstrap circuit and the current sink circuit are activated. When the current in the write head nears and/or slightly surpasses the desired destination current level, the bootstrap circuit is deactivated and the pull-up device is thereafter immediately activated for a predetermined period of time.

Abstract: A phase-synchronizing circuit includes a phase error detection circuit detecting a phase-error in a given clock signal and producing an output indicative of the phase-error as a first phase-error signal, a phase-error creating circuit creating a second phase-error signal determined so as to minimize a time for establishing a phase-synchronization for the clock signal, and a selection circuit selectively supplying the first or second phase-error signal selectively to a phase control circuit.

Abstract: A plurality of digital signals having total data rates of n bit/s or less are input to a digital recording device recording digital signals having a data rate of n bit/s. The digital signals are subjected to format-conversion for the digital recording device to be recorded therein. Furthermore, signals having a data rate of n/i1 bit/s or less are subjected to format-conversion to be recorded i1 times in the digital recording device. In the case where the data rate of the digital signals to be input is n/j bit/s, the digital signals are subjected to format-conversion so that the amount of data capable of being recorded per unit time is decreased by i/j; thus, the digital signals are recorded for a long period of time under the condition that the data recording time is prolonged j times.

Abstract: In a magnetic disk device and other memory devices, the scale and cycle of disturbance applied to each memory device are monitored to make a distinction between a harmful shock and harmless vibrations and detect the disturbance. Values at at least two points, of a waveform signal corresponding to the disturbance are captured. A) The above distinction is carried out from the size or magnitude of the inclination of a straight line defined by the two points. B) The function of capturing and storing the waveform signal corresponding to the disturbance as digital data, and outputting a slice level value for providing suitable detection sensitivity from a conversion table based on the digital data, or correcting and adjusting it and outputting the result is further set.

Abstract: An information recording device which records information at a high recording density such that an error rate is reduced. In particular, an information recording device that includes a recording head, arranged near or to be close to the recording medium, for applying magnetic fields to the small regions when the recording head relatively moves with respect to the recording medium to pass on the small regions of the recording medium, and a recording head controller for controlling the recording head to cause the recording head to apply magnetic fields to the small regions in a free region of the recording medium in a standby state in which at least information is not recorded on the recording medium to uniform the directions of magnetization of the small regions so as to erase the information in the predetermined free region.

Abstract: A rotating storage medium has an index mark-indicating sequence recorded thereon, the index mark-indicating sequence comprised of bits distributed over plural servo wedges. The index mark-indicating sequence is comprised of at least one bit in each of a specified number of plural servo wedges per track, the specified number forming a subset of the servo wedges of the rotating storage medium. The specified number (subset) of plural servo wedges per track preferably is comprised of the servo wedge which contains the index mark a predetermined number (m−1) of consecutive servo wedges. The subset of plural servo wedges may be positioned to precede and include the servo wedge which physically contains the index mark, or may be offset therefrom. Both the synchronization marks of the plural servo wedges and the index mark-indicating sequence are preferably fault tolerant.

Abstract: A method and apparatus for characterizing a magnetic disk (40) of the type that contains data to be read by a magneto-resistive type head (18) in proximity thereto is disclosed. The method includes writing a continuous signal onto the disk, and reading back the signal written onto the disk (40) using the magneto-resistive type head (18). The read back signal is compared to a threshold value (58), and areas of said disk at which energy contained in said read back signal occurs above said threshold value (54) are mapped. The energy content is measured by accumulating oversampled signal values from the read back signal during a time at which said read back signal exceeds the threshold value (58).

Abstract: A disk apparatus having a ramp loading mechanism. A disk medium on which second servo patterns have been written in a landing area on the medium at a finer interval than that of first servo patterns written in a data area is used. When a head is moved from a ramp to the landing area on the medium, a lead-in processing unit performs a servo lead-in on the basis of the second servo patterns written in the landing area at a fine interval.

Abstract: The present invention relates to a method of providing error margin information for threshold errors associated with a digital peak detector. The method comprises comparing a plurality of peak sample values associated with the digital peak detector to a threshold margin test level and incrementing a counter each time the threshold margin test level exceeds one of the plurality of peak sample values. The value associated with the counter relates to an amount of threshold margin associated with the digital peak detector. The present invention also relates to a method of providing error margin information for peak shift errors associated with a digital peak detector. The method comprises identifying relevant peak sample data points associated with each of a plurality of detected peaks and determining a peak shift amplitude associated with each of the detected peaks using the identified relevant peak sample data points.

Abstract: According to one embodiment of the present invention, a fly height of a read/write head in a disc drive is actively controlled as the read/write head is positioned over a rotating disc with a patterned media. The patterned media includes ridges and grooves in servo wedges in the patterned media. According to another embodiment of the present invention, an estimated fly height of the read/write head is compared with a desired fly height to generate a control signal. The control signal is used to apply a voltage difference across a piezoelectric layer joining the read/write head to a slider to move the read/write head relative to the slider and adjust the fly height of the read/write head. According to another embodiment of the present invention, a map of ridges and grooves in the patterned media is generated and the fly height of the read/write head is actively controlled based on information in the map.

Abstract: A method and system for servo error integration in read-channel equalization are described. In the present invention servo error is integrated into an equalizer. Also described in the present invention are methods and systems for determining the servo error.

Abstract: A method, devices, and an article of manufacture for reducing magnetic instability in a magnetoresistive read head of a combined read-write head after writing data onto a magnetic storage medium. The last write pulse polarity that results in the least amount of magnetic instability in the read head is determined, and is referred to as the designated polarity. Then, after a set of write pulses is written, it is determined whether the last write pulse has the designated polarity. If the last write pulse does not have the designated polarity, then an additional write pulse with the designated polarity is written. Thus, the last write pulse before a read always has the designated polarity, thereby reducing the magnetic instability of the read head, and consequently improving read head performance.

Abstract: A recording/playback apparatus accommodates a recording medium in a cassette shell and performs recording and/or playback with respect to the recording medium cassette provided with a cassette-side antenna connected to an in-cassette memory. The playback apparatus includes a recording/playback mechanism, a cassette holding member, a cassette passing member and an apparatus side antenna. The apparatus side antenna effects communication through the in-cassette memory and the cassette-side antenna. An electric wave transmission portion is formed in a portion of the cassette holding member opposed to the cassette-side antenna. The apparatus-side antenna is arranged in correspondence with the electric wave transmission portion.

Abstract: A “snake-in-the-box” (SITB) code is used to encode a track identifier (TID) in a servo sector of a disk drive to identify a particular track on the disk surface. The SITB code describes the longest possible vector that can fit into a finite space, and comprises a type of difference-preserving code. When an SITB code is used for the TID, any single bit error in the TID will be detected. The Hamming distance for TIDs of adjacent tracks is 1 with a SITB code, as with a Gray code. However, for TIDs of tracks that are not adjacent, the Hamming distance is at least 2 with a SITB code.

Abstract: A single disk drive uses data mirroring techniques to store data within the drive. Each piece of data received by the disk drive for storage is written to at least two different storage locations within the drive. Preferably, each of the different storage locations occurs on a different disk surface, but within the same cylinder, of the drive. In one embodiment, each disk surface in the disk drive is divided into N distinct regions that are each 360/N degrees out of phase with one another. Each region on a disk surface is aligned with a corresponding region on each other disk surface in the disk drive. Data stored in each region on a disk surface is then mirrored within a different region on a different disk surface in the drive. Using such a technique allows a significant reduction in latency to be achieved during subsequent read operations.

Abstract: Recording/reproducing apparatus for recording/reproducing serial information stream of A/V signals comprising packets of information signals, such as MPEG Transport Packets, on/from a recording medium. The apparatus includes a time stamping unit for time stamping received information packets in accordance with a time stamping clock reference, a writing unit for recording the information packets in accordance with a write clock reference, and a reading unit for reproducing the information packets in accordance with a read clock reference. All clock references are derived from a single crystal clock reference. The read clock reference has a frequency equal to the frequency of the single crystal clock reference, this frequency being an integer multiple of the frequency of the write clock reference. The time stamp clock reference has a frequency derived from the single crystal clock reference by a digital counter.

Abstract: A circuit (50) and method are presented to provide positive biasing voltages to an MR head (18) in a mass data storage device (10). The circuit (50) includes upper (56) and lower (62) driver transistors to respectively bias respective opposite ends of the MR head (18) with positive voltages. A feedback circuit (58,60,74,84) controls a lower voltage (63) of the positive voltages to be a value as close as possible to a saturation voltage of the lower driver transistor (62), without causing the lower transistor (62) to saturate. Since the MR head (18) is connected between the upper (56) and lower (62) driver transistors, maintaining the lower voltage (63) just above the saturation voltage of the lower driver transistor (62) reduces the common mode voltage across the MR head (18) to a minimum value.

Abstract: A recording and reproducing method and apparatus for an optical disk of the phase transition type is provided. This method comprises the steps of deciding at random to invert or not to invert write data that has a predetermined block length; inverting the write data if the decision is to invert the write data; and recording either the non-inverted write data or the inverted write data into the photo-sensitive record layer. A synchronizing signal is recorded before the write data and/or dummy data after the write data in the way such that thermal stress is less likely to occur. A record end position can be determined precisely by detecting a stop pulse.