Abstract: In a disk drive system, a servo controller is operative to perform a process of inhibiting write operations for writing data to tracks of a disk during a head settling period following a track seek operation. During each of a first plurality of sampling intervals transpiring during a first time period, the servo controller determines a present position value indicative of the position of the head during the present sampling interval, and also determines a predicted position value indicative of the position of the head during a subsequent sampling interval. Also during each of the first plurality of sampling intervals, the servo controller determines: whether the present position value is within a first error margin from the center of a target track; and whether the predicted position value is within the first error margin. If the present position value and the predicted position value are both within the first error margin, the servo controller enables write operations.

Abstract: A discrete-time filtering method for identifying defects in a magnetic medium, comprising the steps of: reading data signals from at least a portion of the medium; sampling the data signals to generate discrete time sample data; processing the sample data in a discrete time filter to detect deviation of the signal corresponding to media defects; and comparing the deviation of the signal to one or more threshold values to identify corresponding defect types on the recording medium. The filter can be configured to have an impulse response substantially matched to deviation of the signal corresponding to media defects.

Abstract: When the amount of position error PE of a magnetic head meets the condition of Ewf>PE>=Eww for two threshold values Ewf and Eww meeting Ewf>Eww, the track is registered in the track information table as a track requiring rewrite and the tracks on both sides neighboring to the track are temporarily write-inhibited. The data of the track is rewritten on another track later so as to maintain the data. By doing this, the offtrack of the recording track can be made smaller without sacrifice of the access speed and the occurrence probability of write fault can be reduced. Furthermore, the reliability of a magnetic disk apparatus can be improved.

Abstract: A system and method for selecting between two biasing modes for biasing magneto resistive heads in a disk drive. A mode selector selects either a voltage biasing circuit or a current biasing circuit to supply the bias voltage or bias current, respectively, to a magneto resistive head. The selection can be based on changes in parameters in the disk drive or magneto resistive heads during disk drive operation.

Abstract: A recording disk has a data area and a servo-burst area alternately arranged with each other in the circumferential direction of the disk. The servo-burst area has a servo-burst pattern having signal sections and non-signal sections arranged with a period &lgr; in the radial direction of the disk. The period &lgr; is expressed by &lgr;=2p×n/m in terms of track pitch “p” of the disk, wherein n and m are integers prime to each other provided that n/m<2.

Abstract: A device for writing information to a magnetic medium includes an inductive head and a write amplifier coupled to the inductive head. The write amplifier receives an information signal, and amplifies the signal to provide a current through the inductive head to generate a flux at the inductive head which flux writes a bit of the information on the magnetic medium. The current for each bit of information is characterized by a rising portion, a peak portion, and a settling portion. A damping network is coupled to the inductive head, and couples a low impedance path to the head and the write amplifier, after the current reaches the peak portion, to divert current from the head to reduce a duration of the settling portion of the current. The write amplifier and damping network are embodied together in an integrated circuit, and are programmable via a serial interface.

Abstract: An amplitude comparator compares to one another amplitudes of data items, which have been read by read heads and amplified by amplifiers. An error identification circuit detects a read level lowering in the read heads according to the result of the comparison. A signal processor references the detection result of the error identification circuit if a read error is detected. If any of the read units has a lowered read level, the cause of the read error is determined to be in that read unit. If none of the read heads has a lowered read level, it is determined that the read error has been caused by other than the read heads.

Abstract: A device is described for increasing the rate at which data may be written to a magnetic data storage medium. The device includes circuitry for amplifying the data and circuitry for writing the data to a data storage medium. The circuitry for amplifying the data includes: circuits for amplifying the data; delaying and amplifying the data; and adding the amplified data and the delayed and amplified data.

Abstract: A magnetic media storage system output circuit includes a filter for filtering an analog output signal from the storage media system before the analog output signal is provided to a read channel. Within the magnetic media storage system a read/write head reads data from a magnetic medium and provides an analog signal representing the data to an output circuit. The output circuit includes the filter for filtering the analog output signal and a pre-amplifier circuit for amplifying and transmitting the analog output signal to a read channel. Preferably, the filter has a linear frequency response and constant group delay below the cutoff frequency. Current on a write current control pin is used to control the cutoff frequency of the filter so that the cutoff frequency will track the data rate. An output signal from the storage media system output circuit is provided to a read channel.

Abstract: A magnetic reproducing apparatus uses a magnetic head to read data recorded on a magnetic recording medium. The signal reproduced by the magnetic head is, in a reading circuit, amplified by an amplifier circuit. A compensation circuit compares the bias voltage across the magnetic head with a reference voltage to detect variation in the bias voltage and compensates for the variation in accordance with the detection result. In the magnetic reproducing apparatus, the amplification factor of the amplifier circuit is set by a control signal fed in via a single switching terminal, and the reference voltage is set in a manner interlocked therewith.

Abstract: An automatic head switching control method and apparatus detects whether an interval between a head switching point of time and a vertical sync signal is 6.5 horizontal sync signal intervals and repeats processes for altering head switching delay data tD, thereby generating a head switching signal having an appropriate head switching point of time and altering only a head switching point of time for one head during the repeat of the altering process. Accordingly, the velocity change of a drum motor does not occur and a control time is reduced as compared to an envelope detection type controller.

Abstract: Dropout produces amplitude and high frequency loss in the read signal produced by reading a magnetic tape. A system for dropout compensation includes an adaptive filter that filters the read signal using multiplicative weighting factors based on an error signal. A detector receives the adaptive filter output and produces a binary signal indicating data written onto the magnetic tape. A shaping filter receives the binary signal and produces an ideal read signal representing the read signal resulting from writing and subsequently reading the binary signal without dropout. A differencer determines the error signal by subtracting the adaptive filter output from the ideal read signal.

Abstract: An apparatus and method of reducing the size of a servo burst and thus increasing the disc surface available for data storage is accomplished by uniquely encoding track information in the gray code of a servo burst on a disc. Each track has a unique sequential track identification number assigned to it. A plurality of sets of servo sectors on each track are encoded with a modulo operation of the track identification number for the track each using a unique modulus. Preferably the sectors are grouped into two sets, i.e., even numbered sectors on each track are modulo encoded with a first modulo operation of the track identification number for the track using a first modulus and odd numbered servo sectors on each track are modulo encoded with a second modulo operation of the track identification number for the track using a second modulus. Decoding the absolute track address is accomplished by decoding the modulo numbers and comparing the even sector modulo numbers to the odd numbered sector modulo numbers.

Abstract: An apparatus and method for minimizing the effects of rotational vibration upon a disc drive having a base deck supporting a rotatable disc and an actuator having a moveable data head. A fixed head is supported over the disc at a predetermined radius and transduces a circumferentially extending frequency pattern written to the disc at a constant frequency to generate a readback signal. A frequency modulation (FM) demodulator generates a rotational velocity signal indicative of application of rotational vibration to the base deck in relation to changes in frequency of the readback signal. A servo circuit controllably positions the moveable data head in response to the rotational velocity signal and servo information readback by the moveable data head. The servo circuit interrupts a data transfer operation between the moveable data head and a host device when a magnitude of the rotational velocity signal exceeds a predetermined threshold.

Abstract: In a tape cassette including a magnetic tape having a plurality of partitions in which recording data is written, numbers P1, P2, P3, . . . respectively assigned to the partitions are arranged in an ascending order from the beginning end BOT of the magnetic tape toward an end EOD thereof. When a partition is newly appended, the last partition is divided, and the region behind the dividing part is used as a new partition which is assigned by a number Pn+1 obtained by increasing the maximum number Pn among the partition numbers which existed before the division, so that partitions can be freely appended or deleted.

Abstract: A magnetic recording control circuit for controlling current through a magnetic recording head includes a switch network, a signal coupler, and a current reducer. The switch network is connected to first and second magnetic recording head node regions and includes first, second, third, and fourth switches each having a variable magnitude conduction path and a control region. The signal coupler includes an input region and a plurality of output regions each connected to the control region of a corresponding switch. The current reducer is connected to the first magnetic recording head node region and shunts current away from the signal coupler.

Abstract: Undershoot and overshoot control circuitry is provided in a write driver circuit to enhance its efficiency and ability to quickly change directions of write current through a write head.

Abstract: When a pin layer magnetic field offset judgment unit judges that a magnetic field in a pin layer of a spin valve head through which a sense current flows in the interference direction has been deviated from a normal direction, a recovery processing unit allows a recovery from the abnormality arising from the magnetic field offset. For example, the direction of the sense current is switched from the interference direction to the assist direction, and the sense current larger than that upon the ordinary reading action is allowed to flow so that the temperature of an antiferromagnetic layer exceeds the blocking temperature, whereby the direction of the magnetic field in the pin layer is modified to the normal direction by the action of a magnetic field generated from the sense current. After the modification, the sense current is returned to have its ordinary value in the interference direction.

Abstract: A drive circuit for a magnetic recording device is provided in which the stray capacitance and stray inductance of the peripheral wiring of the drive circuit is reduced. Also, the drive circuit increases the read/write frequency of data and the recording density of the magnetic recording device. Specifically, the drive circuit contains a write driver, a read preamplifier, a write predriver, a read postamplifier, and a current signal detecting circuit. The write driver inputs write data and outputs a corresponding writing current to a write head to store information onto a magnetic disk. The read preamplifier supplies a bias current to a read magnetic head to sense information stored on the magnetic disk and amplifies the information as output data. The write predriver inputs a write data signal via a data signal line and a write mode signal and supplies the write data to the write driver based on the write mode signal.

Abstract: Apparatus and method for dynamically programming the magnitude of read bias and write currents in a disc drive head (30A, 30B). A digital input value is provided to a register (80) of a digital to analog converter (76, 78), the digital input value indicative of the desired magnitude of the head current. A multiplier (82) of the digital to analog converter (76, 78) multiplies the digital input value by a reference voltage to generate an output voltage. The differential voltage between the reference voltage and the output voltage controls the source to drain resistance of a transistor (106) connected in series with a preamp voltage source (114, 120) of a preamp circuit (70). By inputting different digital input values, the source to drain resistance of the transistor (106), and hence the magnitude of the current generated by the preamp voltage source (114, 120), are precisely controlled.