Abstract: A disk drive system is disclosed that includes a disk device coupled to control circuitry. The control circuitry includes a read channel with a detector that detects a bit sequence associated with Gray codes and delays indications of the bit sequence detection to handle phase shifts. The detector generates a Gray code detection signal in response to the delayed indications. The control circuitry processes the Gray code in response to the Gray code detection signal.

Abstract: Bias recording is used to record servo patterns on magnetic tape. With use of bias recording, a faster recording process may be provided relative to conventional pulse recording processes. A servo pattern recording method includes providing a servo band along at least a portion of a length of a tape. Bursts of a first signal are recorded in a first servo track of the servo band along the length of the tape and a second signal, e.g., a continuous signal, is recorded in at least a second servo track of the servo band along the length of the tape. The second servo track is recorded adjacent to the first servo track and at least one of the first signal and the second signal is recorded using a bias signal at a bias frequency summed with a record signal at a record frequency. A system for carrying out the bias recording of servo patterns is also described.

Abstract: A magnetic disk unit includes a housing which accommodates a magneto-resistive element and a magnetic disk, a temperature sensor for detecting a temperature within the housing, a circuit for detecting a resistance value of the magneto-resistive element, and a current control unit for controlling a sense current which is supplied to the magneto-resistive element, based on the detected temperature detected and the detected resistance value.

Abstract: Apparatus for detecting defect in a recordable medium such as a disc drive is disclosed. The apparatus includes a recording system which write and read test data on the medium. The apparatus also includes a first comparator for comparing the read data to a first threshold. A first and a second counter, operably connected to the first comparator, are incremented when the read data exceeds the first threshold. When the first counter obtains a first count value, a first defect signal is produced. Data domains associated with the recordable medium are marked as bad in response to the first defect signal. When the second counter obtains a second count value, a second defect signal is produced and data sectors associated with the recordable medium are marked as bad in response to the second defect signal. A method for detecting defects in a recordable medium is also disclosed.

Abstract: A disc drive includes a base and a disc rotatably attached to the base. The disc drive also includes an actuator assembly rotatably attached to said base and a device for moving the actuator assembly. The disc drive also includes at least one sensor for sensing disturbances to the disc drive. The disc drive has a system microprocessor in electrical communication with the sensor. In the event a read error is detected, a plurality of sets of corrective procedures are stored in the random access memory of the microprocessor. The system microprocessor executes the sets of corrective procedures in an order in response to the sensed disturbances input to the system microprocessor.

Abstract: The present invention provides a method for magnetic transfer, the method including the steps of arranging a pair of permanent magnets each having magnetic field symmetrical to the axis of the magnetic pole and with the same polarities facing to each other with the axis of the magnetic pole running perpendicularly to the surface of the slave medium, and arranging two pairs of said permanent magnets at adjacent positions so that the adjacent magnets have the poles with opposite polarities adjacent to each other, rotating the slave medium or the two pairs of permanent magnets in track direction, and applying magnetic field in track direction on the surface of the slave medium, performing initial DC magnetization on the slave medium in advance in track direction, bringing the master carrier for magnetic transfer and the slave medium processed by said initial DC magnetization closely together, and performing magnetic transfer by applying magnetic field for transfer in a direction reverse to the direction of the i

Abstract: A method for forming a termination for a magnetic write head in which a magnetic write coil having an inner turn and an outer turn is formed on a wafer. A bottom capacitor plate for a capacitor on the wafer. A resistor having a first terminal and a second terminal is also formed on the wafer. A dielectric layer is formed over the bottom capacitor plate for the capacitor. A top capacitor plate is formed on the dielectric layer. An overpass lead is formed between the inner turn of the coil and one of the bottom capacitor plate and the top capacitor plate. The first terminal of resistor is connected to the capacitor plate that is not connected to the inner turn of the write coil. The second terminal of the resistor is connected to the outer turn of the write coil. An impedance formed by the write coil, the capacitor and the resistor substantially equals a characteristic impedance Z0 of an interconnect circuit that will be connected to the write coil.

Abstract: There is disclosed a pattern matching technique for comparing (a) signals representing detected magnetically recorded characters against (b) a set of predetermined idealized reference signals representing those characters. The pattern matching techniques involves a correlation of coefficients. The characters are encoded as data in the form of binary signals in which one type of bit has a greater width and the other type of bit has a lesser width. Techniques are disclosed to compensate for various distortions in the demodulated characters from the magnetic stripe. These distortions may be due to a loss of magnetic head resolving power, contamination and scratches on the magnetic medium and equipment drift. Techniques are disclosed for normalizing the width of each segment that corresponds to a character. Techniques are also described for detecting the starting point of the segment that represents a character. A technique is described to avoid errors due to abnormal signal peaks.

Abstract: A method and apparatus that adjusts FIR taps based upon Viterbi margin counts. The FIR taps are adjusted by a) selecting one of N tap pairs for adjustment, b) adjusting the tap pair up one count and down one count, c) determining whether adjusting the tap pair up or adjusting the tap pair down provides a lower Viterbi margin count from the Viterbi detector and d) selecting the tap adjustment for the pair that provides the lower Viterbi margin count.

Abstract: A signal from a storage medium is processed in a data channel to form digital data. An amplifier and a sampler convert the storage medium signal into a timed sample sequence. A first equalizer and adjuster operates to equalize the timed sample sequence and to adjust the gain of the amplifier and timing of the sampler in a preamble segment of the signal. A second equalizer and adjuster circuit to equalize the timed sample sequence for detection and to adjust the gain of the amplifier and the timing of the sampler operates in a user data segment of the signal. An FIR equalizing filter in the second equalizer and adjuster circuit is controlled by a set of parameters to accurately equalize a large range of waveforms in the user data segment of the signal and an FIR equalizing filter in the first equalizer and adjuster circuit is controlled by a smaller set of related set of parameters adapted to accommodate rapid adjustment during synchronization in the preamble segment of the signal.

Abstract: A magneto-resistive asymmetry compensation system includes a linearizer (61) interposed in a data path and a control loop (63). The control loop uses signal estimates from an interpolated timing response unit (25) to derive a magneto-resistive asymmetry error. The error term is used to obtain a control scaling input to the linearizer. The linearizer functions to multiply the scaling multiple to the square of the input signal and then add it back to the input signal.

Abstract: A method and apparatus are provided for thermal asperity recovery for word sync detection in data channels. A word sync field contains a plurality of word sync patterns. A word sync detector receives a read signal of the word sync field. The word sync detector identifies a first subset of the plurality of word sync patterns and starts a customer data read. When the word sync detector fails to identify the first subset of the plurality of word sync patterns, the read signal of the word sync field is received again. Then the word sync detector identifies a second predefined subset of the plurality of word sync patterns and starts a customer data read. A single word sync field is used instead of the conventional dual word sync fields required for each sector. The second predefined subset of the plurality of word sync patterns is smaller than the first subset. For example, when the first subset is defined as 4 of 8, the second predefined subset is 2 of 8.

Abstract: An active damping circuit including an H-bridge circuit having an inductive load and a switching circuit, an impedance circuit responsive to a bias signal to damp the H-bridge circuit, and a bias circuit to generate the bias signal responsive to the voltage drop across the H-bridge circuit.

Abstract: An apparatus and method for transferring data between a read/write transducer and a data storage medium provides for improved track format efficiency. Data is written to a data sector of the data storage medium using a write current waveform developed in the read/write transducer. The write current waveform is typically at one of several possible states following writing of the data to the data sector. According to the present invention, a transition pattern is generated and used for transitioning the write current waveform from the state following writing of the data to a known state consistent with coding constraints of the data channel. A predetermined data pattern associated with the known state of the write current waveform is written to a pad field of the data sector. The transition pattern and the predetermined data pattern are used to resolve detector and parity post-processor closure decisions during a sector read operation.

Abstract: The present invention provides a method for magnetic transfer and an apparatus for magnetic transfer, by which it is possible to transfer a transfer pattern with high quality from a master carrier for magnetic transfer to a slave medium by magnetic transfer regardless of position of the magnetic pattern. The method and the apparatus for magnetic transfer according to the present invention are used to apply magnetic field for transfer by bringing the master carrier for magnetic transfer into contact with the slave medium, the master carrier having a magnetic layer formed on a portion corresponding to an information signal on surface of a substrate, and the slave medium being a magnetic recording medium for receiving magnetic transfer after performing initial DC magnetization by a magnetic field by more than 1.

Abstract: The actual data recording area on a recording medium is expanded by reducing a gap area between blocks of data for compensating for a delay time of data conversion while recording and reproducing data in a data recording and reproducing device. Based on a servo sector signal, a data sector generator circuit generates a write data sector signal indicating a timing of data recording in a data recording area, and outputs the write data sector signal to a delay circuit and a selector having two input ports and one output port. The delay circuit generates a read data sector signal by delaying the write data sector signal by a certain period, and outputs the read data sector signal to the selector. The selector outputs the write data sector signal when a write mode signal is active, and outputs the read data sector signal when the write mode signal is inactive.

Abstract: The present invention provides a method for magnetic transfer, which including the steps of: arranging permanent magnets each magnetized symmetrically to the axis of the magnetic pole with the same polarities facing to each other and with the slave medium interposed between, and disposing the slave medium perpendicularly to the axis of the magnetic pole, rotating the slave medium or the permanent magnets in track direction; and applying magnetic field in track direction on the surface of the slave medium, whereby: after initial DC magnetization has been formed on the slave medium in advance in track direction, the master carrier for magnetic transfer and the slave medium processed by the initial DC magnetization are brought closely together, and a magnetic field for transfer in reverse direction to the direction of the initial DC magnetization on the surface of the slave medium is applied in track direction, and magnetic transfer is performed.

Abstract: Defect management for automatic track processing without an ID field, processes defect information for a track on a magnetic media within a disk drive system. A system which uses any method of defect management including linear replacement, sector slipping, cylinder slipping or segment slipping, can be supported. A physical sector number for each sector is translated to a logical sector number relating to the order of data on a track. This translation of the physical sector number to a logical sector number for automatic track processing can be accomplished using any one of three methods: 1) a track defect table can be built in the buffer RAM; 2) the defect information can be written in the header of every sector; or 3) a system FIFO, located in the onboard logic, can be used to manage the defect list. In the second method, the header subfield comprises four defect records.

Abstract: A reproduction signal 10 is processed in an AD converter 4 and an equalizer 16 to be a decoder input signal 12. The decoder input signal 12 is used to calculate a phase error signal 25 and a quality judgement signal 26. A phase-frequency error detection circuit 22 retains a sign of the phase error signal 25 obtained when the quality judgement signal 26 is changed in quality from “good” to “bad”. The phase-frequency error detection circuit 22 then outputs, as a phase-frequency error signal 27, the phase error signal 25 when the signal quality is “good”, and a given value corresponding to the retained sign when the signal quality is “bad”. A voltage controlled oscillator 9 generates a recovered clock signal 11 whose frequency is based on the oscillation control signal 15 generated by the phase-frequency error signal 27.

Abstract: The present invention pertains to an apparatus and method for recording data in a variable bit density disc drive. The disc drive includes a recording surfaces, each having a corresponding head for recording data on the recording surface. At least one head is operated at a different recording frequency from the other heads, creating a variable bit density for the different recording surfaces. The combination of head recording frequencies is determined following an error testing operation and a unique physdisc lookup table is created based on the determined recording frequencies. The physdisc lookup table is used to allocate data sectors and to convert between logical and physical block addresses.