Abstract: A write head is described having a switchable damping resistance coupled in parallel with an inductor. The damping resistance is decoupled from the inductor by rendering a transistor nonconductive when a direction of current in the inductor changes. The damping resistance is then coupled to the inductor before oscillations begin in the current in the inductor. The decoupling of the damping resistor eliminates power dissipation in the damping resistor during a change in the direction of current in the inductor.

Abstract: An information handling system, such as a disc drive, includes a base, a disc stack rotatably attached to the base, and an actuator assembly movably attached to the base. Attached to one end of the actuator assembly is one or more transducers. The disc includes data areas and servo areas written at angular locations on the disc. The disc drive also has a disc drive controller which includes a motor speed controller, a write gate controller, and a device for predicting the disc speed at an upcoming servo and disabling the write gate if the predicted disc speed is outside a selected range of disc speeds. The device for predicting the disc speed may further include an abort signal generator that produces an inhibit write gate signal in response to the predicted disc speed being outside the selected range of disc speeds.

Abstract: A circuit (50) and method are provided for generating a signal (84) indicating an open impedance fault of a coil (56) of a write head (18) of a mass data storage device (10). The circuit (10) includes a differential amplifier (51) with the electrical component (56) being connected as a load in a first leg thereof. An impedance element (64) is provided in a second leg of the differential amplifier (50), and a pair of bipolar transistors (52,54) are respectively connected in the first and second legs. The pair of bipolar transistors (52,54) have a constant bias voltage (Bias) applied to inputs thereof, and an output circuit is connected to an output node of the first leg of the differential amplifier (51).

Abstract: A recording equalizer for correcting a write timing of magnetic information when the magnetic information is recorded with a magnetic recording head on a magnetic recording medium, includes a buffer for storing a recording object bit and bits before and after the recording object bit and a calculator for calculating a precompensation parameter using the bits stored in the buffer. The calculator calculates the preconpensation parameter of the recording object bit by linearly adding influence of a transition existing at a two-previous bit of the recording object bit, influences of a transition at a one-previous bit of the recording object bit and influences of a transition existing at one-following bit of the recording object bit and further adding an offset. The offset is determined to a value such that a write timing of the magnetic information is corrected always in a delaying direction.

Abstract: The present invention may be regarded as a disk drive comprising a disk with a reserved sector for storing a data-sector channel parameter, and a data sector for storing data. The disk drive further comprises a read channel circuit comprising a parameter register, and a non-volatile semiconductor memory (NSM) storing a reserved-sector channel parameter that is selected by using a parameter calibration procedure performed for the disk drive. A disk controller retrieves the reserved-sector channel parameter stored in the NSM, programs the parameter register with the retrieved reserved-sector channel parameter in order to configure the read channel circuit to recover the data-sector channel parameter stored in the reserved sector, and programs the parameter register with the recovered data-sector channel parameter so that the read channel circuit is configured to recover the data stored in the data sector.

Abstract: An information storing device and an information processing device having a memory for registering a plurality of working modes at recording/reproduction and a switching circuit for selecting one of the plurality of working modes, which select the optimum working mode automatically or by an instruction of ah operator according to power supply capacity of a device of higher rank to effect recording/reproduction.

Abstract: An improved servowriting system and method whereby errors introduced into the written servo information are reduced or eliminated for greater servowriting accuracy. Accuracy is enhanced by one or more of the following improvements: 1) optimizing write current and write frequency to minimize write width modulation; 2) optimizing the RPM of the storage medium to minimize random mechanical vibration; and 3) providing a clip level check to eliminate the introduction of large errors in product servopattern. The proposed improvements provide substantial rejection of, for example, mechanical and magnetic disturbances, ensuring a robust servowriting process.

Abstract: A circuit and a method of operation for detecting a bit sequence from an analog waveform representing the bit sequence and at least one other parameter associated with the analog waveform are disclosed. Detection includes digitizing the analog waveform and at least one other parameter using at least one analog to digital converter. The resulting digital numbers are synchronized in time by a plurality of registers so that the outputs of the registers always change simultaneously. The outputs of the registers are concatenated to form an address. The address is input into a read-only memory that looks up a most likely bit detected that has been predetermined for that address and stored in the read-only memory. The bits read from the read-only memory by the addresses are output periodically to form the bit sequence.

Abstract: A novel magnetic data storage method is disclosed for storing digital data in a magnetic medium. According to the present invention, the digital data is represented by the interval between two consecutive biphasic magnetic pulses recorded in the magnetic medium. In addition, additional data can be encoded in the pulse width of each biphasic magnetic pulse so that higher data encoding ratio can be achieved.

Abstract: A magnetic disk read/write circuit comprises a core having a pair of coils wound such that signals supplied to the coils becomes opposite in phase and a read circuit having a first input terminal connected to one of terminals of a read head through one of the coils to receive a read signal from the read head and a second input terminal connected to the other terminal of the read head through the other coil to receive the read signal from the read head or a write circuit in which the read head is a write head, the signal at the first input terminal is a signal at the first output terminal and the signal at the second input terminal is a signal at a second input terminal.

Abstract: An apparatus (and method) is provided that reduces thermal interference in the read signal of a disk drive. A variable or programmable resistance is used to change the transfer function of a filter in the read channel of the disk drive to filter the read signal. The filter has a first transfer function (first cut-off frequency) related to the programmed resistance during normal operation of the disk drive (i.e. when thermal interference is not detected). When thermal interference is detected in the read signal, the resistance is programmed to another value resulting in the filter having a second transfer function (second cut-off frequency). The resistance element includes a transconductance amplifier whose transconductance is variable or programmable to different values resulting in different programmable transfer functions (or one of a multitude of cut-off frequencies) for the filter.

Abstract: In the recording method of the present invention, the surface of a master information carrier facing a recording medium becomes slightly concave in its center when the master information carrier is placed upon and brought into tight contact with the recording medium, and information signals are transferred and recorded onto the recording medium. The recording method of the present invention can be widely used for producing disk-type recording media with a hole such as magnetic disks, photomagnetic disks and optical disks. The recording method of the present invention achieves quick and productive production of a very flat and smooth recording medium that is free of fine dust. Furthermore, high-density information signals can be recorded evenly and firmly on the whole surface of the magnetic surface of the magnetic recording medium.

Abstract: A system and method for acquisition signal error estimation is provided which uses one or more past values of the sequence to determine the nearest ideal sample value. According to one embodiment, four consecutive samples are used. According to another embodiment, two samples are used. The acquisition signal error estimator maybe used in conjunction with gain, DC offset, or magneto-resistive asymmetry control loops in a sampled amplitude read channel.

Abstract: A magnetic disk including a plurality of servo sectors and data sectors along a circumference thereof includes full-format servo sectors which are successively arranged in a radial direction of the disk and which include track information and short-format servo sectors which are arranged between the full-format servo sectors not to be successive in a radial direction of the disk and which include position error signals. The short-format servo sectors do not split the data sectors.

Abstract: The present invention achieves technical advantages as an overshoot circuit (30) for a voltage source/impedance based write coil driver circuit (10) accurately controlling the current (IW)through a coil (LH) that is used to write data to a magnetic medium. The circuit (30) improves the characteristics of the coil.

Abstract: A magnetic disk apparatus has: a head (2) that performs data recording and playback while moving relative to a magnetic disk (26) rotating at the prescribed speed; an actuator (3) that positions said head relative to said magnetic disk (26); and a controller (4) that detects the position of said head by means of servo sector that have positioning information recorded magnetically on said magnetic disk (1) and performs control to position said actuator (3) by means of this detection signal, wherein said magnetic disk (1) has at least a part in which the arrangement of tracks is spiral. The magnetic patterns on the disk include a servo sector and a data sector both formed on the same spiral track. The servo sector includes burst patterns for servo control.

Abstract: The present invention may be embodied in a method for minimizing adjacent track data loss due to a shock event occurring during a write operation in a disk drive. The method includes providing a plurality of adjacent concentric data tracks, for storage of user data, that are spaced-apart by a track pitch. The plurality of data tracks are allocated into a first set and a second set such that the data tracks of the first and second sets are interleaved physically with one another. A first series of logical block addresses are assigned to the first set of data tracks such that the first series of logical block addresses are consecutively numbered between successive ones of the first set of data tracks. A second series of logical block addresses, which consecutively follow the first series of logical block addresses, are assigned to the second set of data tracks such that the second series of logical block addresses are consecutively numbered between successive ones of the second set of data tracks.

Abstract: A sampled amplitude read channel is disclosed for magnetic disk storage systems utilizing a read head exhibiting a non-linear response such as a magneto-resistive (MR) read head. A sensor of the read head is adjusted to operate in a region of its response that provides optimum gain even though it may be a region of higher non-linearity. To compensate for the non-linearity introduced into the read signal, the read channel further comprises an adaptive non-linear correction circuit that is adaptively tuned by a least-mean-square (LMS) adaptation circuit. The analog read signal is sampled and the discrete time samples equalized into a desired partial response prior to sequence detection. The non-linear correction circuit is inserted into the read path prior to the sequence detector in order to attenuate the non-linear distortions that would otherwise degrade the performance of the sequence detector.

Abstract: A method for detecting an asperity in a non-data parking zone of a disk in a hard disk drive. The method includes the steps of moving the heads of the disk drive adjacent to the parking zones of the disks, and then detecting asperities in the parking zones with a thermal asperity detection circuit.

Abstract: A signal processing device for analog-to-digital converting a burst signal has a feature of selecting a data bus to notify a disk control device of a conversion result via an NRZ data bus. The disk control device stores the result of the analog-to-digital conversion of the servo positional signal. The positional signal of a head of the disk device is digitalized in a R/W channel. Sampling for digital conversion is performed in only a window which is defined only in the vicinity of peaks of the positional signal. The values of peaks which are obtained by sampling are averaged by an averaging circuit. This enables the influence of noise occurred outside of the window to be eliminated. Although the noise in the window is sampled, its adverse influence is suppressed by the averaging processing.