Abstract: Frequency response is characterized for mechanical components of a multirate system operating in a closed-loop environment. A disturbance is injected at the frequency of interest and at each of the alias frequencies thereof as an input into the multirate system, and a matrix equation composed of resulting measurements of the response of the multirate system is solved to compute the frequency response at the frequency of interest and at each of the alias frequencies. The resulting frequency response can be used to synthesize the transfer function of the entire system, which allows simulation and evaluation of the relative performance of multiple controller designs without the need for further frequency response measurements.

Abstract: A highly efficient and reliable reproduced signal evaluation method and an optical disc drive using that method in which assuming that the number of 2T's appearing successively in a predetermined evaluation bitstream is i, the evaluation bitstream is divided into a main bitstream (5+2i) long and sub bitstreams at the ends of the main bitstream. The check process to determine whether a predetermined evaluation bitstream is included in the binarized bitstreams is replaced with a main bitstream agreement check. This can prevent an increase in the circuit size. At the same time, by separately summing up for each main bitstream the calculated results of Euclidean distance between the reproduced signal and the target signal corresponding to the evaluation bitstream, the size of an evaluation summing circuit can be reduced.

Abstract: Frequency response is characterized for mechanical components of a multirate system operating in a closed-loop environment. A disturbance is injected at the frequency of interest and at each of the alias frequencies thereof as an input into the multirate system, and a matrix equation composed of resulting measurements of the response of the multirate system is solved to compute the frequency response at the frequency of interest and at each of the alias frequencies. The resulting frequency response can be used to synthesize the transfer function of the entire system, which allows simulation and evaluation of the relative performance of multiple controller designs without the need for further frequency response measurements.

Abstract: A HDD comprising a temperature sensor disposed inside the HDD configured to periodically measure temperature inside of said hard disk drive; a magnetic disk; a read head; a write head; memory for storing RWO data. The RWO data is a function of a distance between the read head and the write head. The HDD also includes a RWO data adjustor configured to adjust the RWO data in response to a change in temperature of the HDD to compensate for a change in the distance between the read head and the write head based on the change in temperature.

Abstract: According to a method for setting the laser beam power applied to reproduce information recorded on an optical disc, information recorded in a region on the optical disc is reproduced using three or more test reproduction powers (S22B), the number of reproductions until the degradation of the quality of the reproduced signal reaches a prescribed value is determined as the degradation number of reproductions (S22F), the relation between the test reproduction power and the degradation number of reproductions is approximated by a curve, and a reproduction power restricting the degradation of the reproduced signal quality to a predetermined amount or less over a certain guaranteed number of reproductions is determined (S25F). In optical reproduction from an optical disc on which information is recorded, the optimum power of irradiation for reproduction can be set, and degradation of the information due to the reproducing light can be prevented.

Abstract: A multilayered optical disk an information recording method and information reproducing method utilizing the disk includes three or more recordable or rewritable information recording layers, which has, among the plurality of information recording layers, at least a first recording layer and a second recording layer located on a side nearer to a light incident surface than the first recording layer, and which respectively has a first test area configured by a plurality of segments in the first recording layer, a second test area configured by a plurality of segments in the second recording layer, and comprising a specific area in which there is recorded information used to determine whether or not the respective segments in the first test area can be used.

Abstract: According to one embodiment, a disk storage apparatus includes a read module, a measuring module, and a compensating module. The read module is configured to read first and second signals recorded on a disk, from which to measure the flying height of a head. The measuring module is configured to calculate the flying height of the head from the first and second measurement signals read by the read module. The compensating module is configured to use the data representing the flying height representing error resulting from superparamagnetic effect, thereby compensating for the flying height measured by the measuring module.

Abstract: According to one embodiment, a non-linearity measurement apparatus includes a first measurement module, a second measurement module, and a calculation module. The first measurement module is configured to measure a component of a first higher harmonic from a reproduced signal of a first signal recorded on a magnetic recording medium. The second measurement module is configured to measure a component of a second higher harmonic from a reproduced signal of a second signal recorded on the magnetic recording medium. The calculation module is configured to calculate a non-linear transition shift of the magnetic recording medium by calculating an arcsine function of a value obtained by dividing the component of the second higher harmonic by the component of the first higher harmonic.

Abstract: According to one embodiment, a magnetic disk drive includes a parameter management table, a parameter adjustment module and an interpolation module. The parameter management table stores a parameter used to write or read data to or from a disk in the parameter management table in association with each of a plurality of predetermined temperature divisions. The parameter adjustment module adjusts a first parameter stored in the parameter management table in association with a first temperature division to a second parameter adapted for the first temperature division if an ambient temperature detected by a temperature detector corresponds to the first temperature division and if the first parameter is unadjusted. The interpolation module updates an unadjusted third parameter corresponding to a third temperature division between the first temperature division and a second temperature division for which the parameter is adjusted based on a result of the adjustment of the first parameter.

Abstract: A method for detecting a thickness of an optical disc is provided. Firstly, a beam intensity signal and a focusing error signal are generated. Then, a first time interval for a focus point of the laser beam to move from a first layer to a second layer of the optical disc is acquired according to the beam intensity signal or the focusing error signal. Then, a second time interval between two peak values of an S curve of the focusing error signal is detected. Afterwards, the thickness between the first layer and the second layer is calculated according to a known S-curve detection range, the first time interval and the second time interval. The S-curve detection range is multiplied by said first time interval and divided by said second time interval to obtain the thickness between the first layer and the second layer of the optical disc.

Abstract: An apparatus for judging an optical disc includes a gain controller, an amplitude detecting unit and an amplitude comparing unit. The gain controller is used for receiving a radio frequency signal from an optical pickup head; and processing the radio frequency signal into an amplified radio frequency signal with a target amplitude according to an amplitude feedback signal. The amplitude detecting unit is used for receiving the amplified radio frequency signal, generating the amplitude feedback signal to the gain controller, and outputting a top envelope amplitude according to an top envelope signal of the amplified radio frequency signal. The amplitude comparing unit is used for comparing the top envelope amplitude with a threshold value to generate a resulting signal, and judging whether the laser beams emitted from the optical pickup head are irradiated on a blank area or a data-recorded area according to the resulting signal.

Abstract: A method for moving magnetic heads in a magnetic recording/reproducing apparatus, which comprises the steps of writing high-frequency signals in the magnetic recording/reproducing tracks; and then, either (i) conducting DC erasing or AC erasing to inspect extra pulse signals reproduced from the erased tracks, or (ii) inspecting concurrently occurring signals of missing pulse and spike pulse, which are reproduced from the written signals, whereby minute protrusions on a surface of the tracks were detected. Reading and writing of information are conducted while the magnetic heads are moved in a manner controlled so that reading and writing of information in specific tracks having defects is avoided. This method enhances reliability and life of the magnetic recording/reproducing apparatus.

Abstract: A magnetic tape apparatus performs at least one of data reading processing and data writing processing on LTO wound around a reel. The magnetic tape apparatus causes the reel to rotate and move the LTO to a position at which the data writing processing or the data reading processing can be performed by a magnetic head. The magnetic tape apparatus is arranged along the width direction of the magnetic tape of LTO, which is driven, to detect medium abnormality that occurred in either a start-end or a stop-end in the width direction of the magnetic tape.

Abstract: According to one embodiment, a magnetic disk includes a disk, a controller and an indicator module. The disk includes a plurality of data sectors. The controller is configured to control data rewrite for reading a first data block stored in the disk and writing a second data block corresponding to the read first data block to a write destination on the disk. The indicator module is configured to embed an indicator indicative of an attribute relating to data rewrite in each sector data in the second data block written to the write destination when the each sector data is written to the write destination.

Abstract: A method for rating an information recording medium according to the present invention includes the steps of: receiving a digital read signal, which has been generated based on an analog read signal representing information that has been read from the information recording medium, and shaping the waveform of the digital read signal; subjecting the shaped digital read signal to maximum likelihood decoding, thereby generating a binarized signal showing a result of the maximum likelihood decoding; and calculating the quality of the digital read signal based on the shaped digital read signal and the binarized signal. If the quality of the read signal is calculated by a PRML method in which a number of zero-cross portions are included in a merging path of a minimum difference metric, the quality is calculated by using only a state transition pattern in which only one zero-cross portion is included in a merging path of a non-minimum difference metric.

Abstract: A method for detecting the obliquity of an optical disc drive is provided. The method includes the steps of calibrating balance gains of TE signals and CE signals with predetermined obliquities of the optical disc drive, curve-fitting and storing a relating function between the predetermined obliquities and the balance gains, calibrating the balance gains of signals for an installed optical disc drive, and acquiring an calibrated balance gain to find the obliquity of the optical disc drive from the relating function.

Abstract: In a magnetic tape drive having a servo read system with at least one read head, the system configured to read servo pattern information as a magnetic tape is moved longitudinally with respect to the at least one read head, the servo pattern comprising a timing-based servo pattern comprising an even number of bursts of sloped magnetic stripes, adjacent bursts oppositely sloped, alternate bursts identically sloped, an embodiment of a method determines the time between detection from the read head of a same stripe of alternate bursts of a pattern; determines the time between detection from the read head of stripes of a burst of a pattern; and determines a ratio of the determined times. The ratio is compared to a threshold, wherein the threshold comprises a differentiation between different servo pattern types.

Abstract: A method for encoding in a holographic disk storage medium is provided. The method includes recording multiple micro-holograms such that the micro-holograms are aligned across a respective plurality of tracks and across a respective plurality of layers at a pre-determined location of an original holographic disk. The method also includes detecting a characteristic waveform signal of a reflected beam from the original holographic disk. The method further includes detecting a second waveform signal from a second holographic disk. The method also includes comparing the second waveform signal with the characteristic waveform signal. The method further includes determining authenticity of the second holographic disk based upon comparison.

Abstract: According to one embodiment, a method of detecting contact of a magnetic head with a magnetic disk by changing the dynamic flying height of the magnetic head in a magnetic disk drive is disclosed. The method can detect a change in the rotational speed of the magnetic disk. The method can detect the contact of the magnetic head with the magnetic disk based on the detected change in the rotational speed.

Abstract: A disc drive system provides increased reliability by detecting and correcting errors associated with bit-patterned media. Write synchronization errors associated with bit-patterned media are addressed by including data storage for temporarily storing data that is being written to the disc drive. The data is read from both the disc drive and the storage medium and compared to detect write synchronization errors. The disc drive system utilizes the identified write synchronization errors for at least one of timing recovery, equalizer training detection, error correction code application, and error recovery.

Abstract: A magnetic head slider inspection device including a motor unit for revolving a disk medium, a slider unit provided with a reproducing head, which is levitated from a surface of the disk medium under force generated by the revolving disk medium, a magnetic field generator positioned at an opposite side of the disk medium with respect to the slider unit for generating a magnetic field substantially perpendicular to the disk medium surface, and a circuit unit for generating the magnetic field from the magnetic field generator, and measuring a resistance value of the reproducing head levitated from the disk medium surface.

Abstract: Touchdown between a read/write head of disk drive and a recording medium is detected based on the variance in the frequency domain of position error signals (PES), each of which is measured after incrementally positioning the read/write head closer to the recording medium, from a baseline PES. The synchronous portion of the baseline PES is quantified and removed from the baseline PES and subsequent PES measurements to remove the effect of the synchronous portion of the baseline PES. The non-synchronous portion of the PES measured at a particular read/write head position may also be removed by synchronously averaging multiple PES measurements for each read/write head position. Detection of touchdown may be based on the rate of change of the variance in the frequency domain of PES relative to a baseline PES, instead of the absolute value of the variance.

Abstract: In one embodiment, a method includes applying one or more whitening filters to an input stream of digitized samples from a magnetic data channel to produce a filtered sequence, performing one or more branch metric calculations to the filtered sequence to produce a branch metric, and applying a multi-state data-dependent noise-predictive maximum likelihood (DD-NPML) detector to the branch metric to produce an output stream. In another embodiment, a multi-channel data storage system includes a head for reading data from a storage medium, logic for applying one or more whitening filters to an input stream of digitized samples from a magnetic data channel to produce a filtered sequence, logic for performing one or more branch metric calculations to the filtered sequence to produce a branch metric, and logic for applying a multi-state DD-NPML detector to the branch metric to produce an output stream. Other systems and methods are described as well.

Abstract: Various embodiments of the present invention provide systems and methods for determining contact with a storage medium. As an example, a data storage system is disclosed that includes: a head assembly and a data processing circuit. The head includes a head disk interface sensor operable to provide a contact signal indicating contact between the head and a storage medium disposed in relation to the head. The data processing circuit is operable to process the contact signal to yield an indication of a contact between the storage medium and the head.

Abstract: This invention provides a magnetic recording medium evaluation apparatus and evaluation method which yield results having good correlation with error rate measurements even when comparing media with different structures. Signals from a function generator are recorded in a magnetic recording medium. The recording signals are also passed through a first digital filter to obtain ideal restored signals. Reproduced signals from the magnetic recording medium are sampled in synchronization with the output from the function generator, and the discrete signals are passed through a second digital filter to obtain restored signals. The outputs from the first and second digital filters are input to an operational amplifier, and the difference between the restored signals and the ideal restored signals is taken for each sampling of the recording signals. The signal-to-noise ratio of the ideal restored signal to the average of the absolute value of this difference is used to evaluate signal quality.

Abstract: In a hard-disc drive, a defect region on the hard disc is classified as corresponding to either thermal asperity (TA) or media defect (MD) by generating two statistical measures. A first measure (e.g., ?1) is based on (i) the magnitudes of one or both of signal values (e.g., equalizer input or output signal values) and the corresponding expected values of those signal values and (ii) the signs of one or both of the signal values and the expected signal values. A second measure (e.g., ?2) is based on the magnitudes of one or both of the signal values and the expected signal values, but not the signs of either the signal values or the expected signal values. The two measures are then compared to determine whether the defect region corresponds to TA or MD.

Abstract: In a hard-disc drive, a defect region on the hard disc is detected by generating two statistical measures (e.g., ?1(k) and ?2(k)) based on signal values (e.g., x[n] or y[n]) and soft-decision values (e.g., L[n]) corresponding to the signal values. The measures are compared to detect the location of the defect region of the hard drive. Using the soft-decision values reduces fluctuations in a ratio of the statistical measures compared to a ratio formed from statistical measures that are not based on soft-decision values, resulting in a more-reliable test for detecting defect regions.

Abstract: There is disclosed a method and apparatus for measuring a signal using a measurement system. The signal has a frequency component that is to be detected by the measurement. The frequency component has a varying phase. The signal has at least one interruption thereto. The method includes: processing the signal with the measurement system to detect the frequency component in the signal and stalling the measurement system before the start of the interruption. The stall period is calculated such that the processing of the signal is resumed: i) after the end of the interruption, and ii) where there is substantially no discontinuity between the phase of the frequency component in the signal at the end of the stall and in the phase of the frequency component in the signal at the beginning of the stall.

Abstract: A disk device and a write method that includes performing a write operation on a first data sector using first servo information, performing the write operation on a second data sector, and determining whether the write operation has been normally performed on the second data sector using a second servo signal.

Abstract: A communication apparatus is configured to execute testing of whether or not the responding module is correctly responding to the plurality of commands transmitted and received between a transmission module and a reception module, the testing being performed via a loop-back mode transmission and reception path configured such that the reception module receives the command transmitted by the transmission module; and during the testing, following procedure is performed, which includes: transmitting the specific command by the transmission module; receiving the specific command by the reception module via the transmission and reception path; deactivating reception of the specific command; and transmitting a command different from the specific command subsequent to transmitting the specific command by the transmission module.

Abstract: An optical disc apparatus of the present invention records and/or reproduces data to/from an optical disc where data is recorded on one of a groove track and a land track. The optical disc apparatus includes an identification section for identifying the type of the optical disc as being either an optical disc where data is recorded or reproduced to/from a groove track or an optical disc where data is recorded or reproduced to/from a land track. The identification section identifies the type of the optical disc while in a state where a focus control is being performed and a tracking control is not being performed.

Abstract: An apparatus and a method for testing spoke sensor are disclosed. A drive unit is started to rotate a test disc to a predetermined rotation speed. A module test unit is electrically connected to a spoke sensor under test of a spindle motor module. The module test unit is started to drive the spoke sensor to detect the spoke signals of the test disc and record the number of detected spoke signals. Within a test time, a comparison unit is used for comparing the number of spoke signals with a threshold, and only when the detected number is larger than a threshold will the spoke sensor be assembled to the product. Thus, the product quality is assured.

Abstract: A method and system for interrogating a thickness of a carbon layer are described. The carbon layer resides on at least one of a magnetic recording head and a magnetic recording disk. The method and system include providing an enhancement film on the carbon layer. The enhancement film is continuous across a portion of the carbon layer. The method and system also include exposing the enhancement film to light from a light source and detecting scattered light from the carbon layer to provide a surface enhanced Raman spectroscopy (SERS) spectrum. The enhancement film resides between the light source and the carbon layer. The method and system also include determining the thickness of the carbon layer based on the SERS spectrum.

Abstract: A method of processing disks on spin stand is disclosed, the spin stand comprising a spindle motor having a rotor. A first disk is clamped to the rotor, wherein the first disk comprises a reference servo pattern. A second disk is clamped to the rotor, and a first head is servoed over the first disk in response to the reference servo pattern in order to position a second head over the second disk at a first radial location. Data is written to the second disk at the first radial location using the second head. The second disk is removed from the rotor while the first disk remains clamped to the rotor.

Abstract: A magnetic head disposed in a slider arranged with an interval with respect to a magnetic disk includes a sensor that is positioned in a stepped-back position from an air bearing surface facing the magnetic disk, an insulating film that is positioned on the air bearing surface and that covers the sensor; a pair of lead films, the lead films being electrically connected to the sensor such that at least portions of the lead films are exposed on the air bearing surface, and being configured to transfer a temperature change of the air bearing surface to the sensor.

Abstract: A method of recognizing a track pitch of an optical disk, adapted for an optical disk player, is provided. The method includes the steps of driving an optical pickup head to a predetermined position, so that the optical pickup head and the spindle motor are a predetermined distance apart, reading a data sector address, and recognizing the magnitude of the track pitch of the optical disk according to the value of the data sector address.

Abstract: Various embodiments of the present invention provide systems and methods for identifying a reproducible location on a storage medium. As an example, a circuit is described that include a media defect detector and an anchor fixing circuit. The media defect detector is operable to identify a media defect, and the anchor fixing circuit is operable to identify a location relative to the media defect. The location is reproducible.

Abstract: A control apparatus for controlling initialization of data stored in a storage unit in response to receipt of an initialization instruction from a host system, includes (a) a register unit that stores inversion bit information indicating a plurality of bits to be inverted in data readout process, (b) a data receiving unit that receives read data and an error correcting code corresponding to the read data, and (c) an inversion unit that inverts part of bits of at least one of the read data and the error correcting code corresponding to the read data on the basis of the inversion bit information in the data readout process after the receipt of the initialization instruction. In the above (a), the plurality of bits to be inverted being part of bits of at least one of read data and an error correcting code corresponding to the read data.

Abstract: In a hard-disc drive read channel, frequency-based measures are generated at two different data frequencies (e.g., 2T and DC) by applying a transform, such as a discrete Fourier transform (DFT), to signal values, such as ADC or equalizer output values, corresponding to, e.g., a 2T data pattern stored on the hard disc. The frequency-based measures are used to detect defect regions on the hard disc and/or to classify defect regions as being due to either thermal asperity (TA) or drop-out media defect (MD).

Abstract: A method for controlling a hard disk drive, includes a track seeking servo routine in which seek time is measured in a mode of the routine after the trajectory mode, the measured seek time is compared with a predetermined period of time, and an alarm mode is induced when the measured seek time exceeds the predetermined period of seek time.

Abstract: An optical disc drive and tracking method thereof are disclosed. The optical disc drive includes an optical pickup head, a slip compensation module, a tracking control module and a tracking drive. The optical pickup head generates a detected signal according to an optical signal from an optical disc. The slip compensation module generates a slip compensation signal according to the detected signal. The tracking control module generates a tracking out signal according to the detected signal and the slip compensation signal and, according to the tracking out signal, the tracking drive drives the optical pickup head.

Abstract: A method of identifying a string or chain of efficient or “good enough” disc operations for processing (a pseudo optimal chain) is provided. A “pseudo optimal chain” comprises a string or chain of operations that, while not necessarily the optimal string or chain, provides an efficient sequence of operations that can be determined by comparing individual operations to predetermined selection criteria. In contrast to a true optimization technique that can require computing up to N! combinations for N operations, the string or chain of efficient or “good enough” disc operations allows for relatively simpler computations.

Abstract: In an optical disk apparatus, the same signal path is used to both reduce an interchannel phase shift in write strategy signals and also to perform the actual writing to the disk. The optical disk apparatus includes a laser diode, a laser diode driver, and a semiconductor integrated circuit. The semiconductor integrated circuit includes a write strategy circuit and a control unit for controlling the operation of the write strategy circuit. Information collection for interchannel delay adjustment is performed through the use of the same signal path as that used for transmitting pulse signals from a pulse generation circuit to the laser diode driver for actual writing to an optical disk. Based thereon, an interchannel delay amount for applying laser light to the optical disk is set, thereby reducing the interchannel phase shift in the write strategy signals.

Abstract: A reference-capacity calculating unit calculates a reference capacity of each of storage devices storing therein data on the basis of an actual capacity of each storage device. A difference calculating unit calculates a difference value between the reference capacity calculated by the reference-capacity calculating unit and the actual capacity of each storage device. A maximum-value retrieving unit retrieves the maximum difference value out of the respective difference values of the storage devices calculated by the difference calculating unit. A defined-capacity determining unit determines a defined capacity, which is an actually-used capacity of each storage device, on the basis of a value obtained by subtracting the maximum difference value from the reference capacity calculated by the reference-capacity calculating unit.

Abstract: A method of preventing data loss in a hard disk drive comprises detecting a write error, performing a write retry operation upon detection of the write error, and storing write retry information in a non-volatile memory before performing the write retry operation. The write retry information comprises location information and data for a sector to be rewritten in the write retry operation.

Abstract: Provided is a digital broadcast receiver capable of displaying a message, a list of titles of contents or the like together with a viewing screen without interrupting viewing of contents. The digital broadcast receiver includes a controller 25 configured to determine whether an optical disc inserted into the receiver is a read-only optical disc or a recordable optical disc and also to control a display screen. Upon insertion of an optical disc, the controller 25 causes a display screen including a first display area and a second display area to be displayed, the first display area displaying digital broadcast or external input contents, the second display area displaying a message indicating that the optical disc is being prepared. In a case where the optical disc is a read-only optical disc, the controller 25 causes only a playback screen of contents recorded in the optical disc to be displayed upon completion of the preparation of the optical disc.

Abstract: An optical disc apparatus for use of an optical disc including a plurality of recording layers sets an amount of correction of spherical aberration for each of the recording layers of the disc during a focus sweep. A photodetector portion produces a signal in response to returned light for each of the recording layers.

Abstract: In an optical pickup device and a method of a focus jump, in order to make optimum correction of spherical aberration responsive to the position of a recording layer at one end nearer a target recording layer than a current in-focus recording layer, the recording layer at the one end being one of recording layers at opposite ends of a plurality of recording layers, spherical aberration correcting means is controlled, and then a focus actuator is controlled, thereby causing a focus to jump to the recording layer at the one end. Next, in order to make optimum correction of spherical aberration responsive to the position of a different recording layer shifted by at least one recording layer from the recording layer at the one end toward the target recording layer, the spherical aberration correcting means is controlled, then the focus actuator is controlled, the focus is caused to jump to the different recording layer, and such a focus jump is repeated until the focus reaches the target recording layer.

Abstract: An apparatus for optically checking magnetic disk defects that makes possible more accurate determination of positions of minute defects by illuminating an area greater than a checkup area with an illuminating beam having a Gaussian distribution is to be provided. The apparatus is configured of a specular reflection detecting device including a detector having a detecting face including an array of multiple pixels, and a processing device that figures out the position of each defect by using, in addition to the output signal from each of the pixels of the detector that detected a specular reflection from the checkup area, also output signals of some pixels out of the multiple pixels having detected the specular reflection from the checkup area of one turn before and the checkup area of one turn after, both adjoining in the radial direction, and determines the type of the defect.

Abstract: To identify the type of a loaded disc, there is provided an optical disc device, comprising: a light source driven by a drive signal with a high frequency signal superimposed; a detector for detecting return light emitted from the light source; and a controller for controlling the amplitude of the high frequency signal to be superimposed on the drive signal, the optical disc device being configured to read data from an optical disc loaded therein by a signal outputted from the detector, wherein: the controller causes the light source to irradiate the loaded optical disc with light in a condition in which a high frequency signal different from a high frequency signal for data reading is superimposed on the drive signal; and the controller identifies a type of the loaded optical disc based on the return light from the loaded optical disc.