Abstract: A detector detects, in read data, a servo address mark of a type indicated by a register. Every time a SAM is detected during a self servo process, a CPU carries out tracking control in accordance with corresponding servo data. The CPU causes a head to write a corresponding type of additional servo data item in a disk at a position offset from the position of servo data containing the detected SAM, by a predetermined distance in a circumferential direction of the disk. Every time sets of servo data, each consisting of various types of data items, are written in the disk, the head is moved by a predetermined pitch in a radial direction of the disk.

Abstract: An apparatus and associated method used to control a disc drive having at least one disc and a transducer positionable relative to the disc by a motor. The motor receives energization through at least one power switch integrated on a semiconductor circuit. Temperature of the circuit is sensed proximate the power switch. A temperature signal is provided which is indicative of whether the sensed temperature meets one of a plurality of different threshold temperatures. The power switch is controlled in one of a plurality of different control modes based upon the temperature signal.

Abstract: Automatic-signal-selecting is provided for controlling which output is supplied from a switch, i.e., a digital signal or an analog signal. The control is carried out based on information selected by manual-signal-selecting and information judged by copyright-information-judging. This structure allows a recording and reproducing apparatus to record the content-prohibited from being recorded in a digital form according to copyright information-in an analog form.

Abstract: A method and circuit for selectively timing amplifier stages of a multi-stage reader amplifier for a hard disk drive system. The reader amplifier includes a first stage, second stage and third stage coupled in series. The method includes the steps of powering the first stage, delaying the enabling of the second stage, and delaying the enabling of the third stage, in order to reduce excursions on the third stage output signal. The circuit includes a logic circuit for successively enabling the second and third amplifier stages.

Abstract: A differential circuit to read differential data from a disk by a current bias on a plurality of read heads includes a read circuit to read the differential data from the disk by maintaining the current bias. The current is below a maximum current of a read head having the lowest maximum voltage of said plurality of read heads.

Abstract: A recording/reproducing apparatus capable of switching over among a plurality of heads with high precision, wherein the apparatus is provided with: a recording/reproducing unit for recording/reproducing signals onto/from a recording medium with a plurality of heads; a generating unit for generating control data for controlling the recording/reproducing unit; and a transmitting unit for transmitting control data generated by the generating unit to the recording/reproducing unit, wherein priority is given in transmission to data for controlling the switching of the plurality of heads over other data.

Abstract: Distinct servo patterns are written on data storage media of a data storage device. Servo patterns of a first type are written for transducers of the data storage device having a first transducer characteristic. Servo patterns of a second type are written for transducers that do not have the transducer characteristic. The transducer characteristic can be a geometric criterion such as read head and write head track width, an operating characteristic such as frequency response, or otherwise. The first servo pattern may be a seamless untrimmed PES burst and the second servo pattern may be a seamed trimmed PES burst.

Abstract: A method and apparatus are provided for closed loop control of head load velocity in rotating media mass storage applications. A novel pulsed current velocity controlled head load/unload circuit is provided that uses the back EMF analog signal to modulate pulse amplitude. A system is thus provided having amplitude modulation of a fixed period current pulse train via back EMF feedback, whereby there is no need to monitor back EMF via A/D conversion circuitry.

Abstract: In a disk device, in a state where no access to the disk is permitted, instead of permitting the head to be driven stepwise whenever step pulses are fed in, the head is inhibited from being driven stepwise until a predetermined period of time elapses after the disk starts being rotated. This helps reduce electric power consumption in such a state. Moreover, when the head has been retracted to its initial position because of an error in the stepwise driving thereof, instead of waiting for step pulses to be fed in from the host and thereby losing much time before the head is moved back to the track at which it was located before the error, the position of the head before the error is stored so that the head can be, by self recovery, moved back to the position before the error without waiting for an instruction from outside the disk device.

Abstract: A method and apparatus for operating a continuous time filter (CTF) (128) of a read/write channel (108) for a hard disk drive (100). The apparatus includes an input multiplexer (220) that receives an analog signal (215) and transmits the analog signal (215) to a read filter circuit (254) when the CTF (128) is in read mode and to a servo filter circuit (256) when the CTF (128) is in servo mode. The apparatus also includes an output multiplexer (222) that receives a read filter output signal (225) from the read filter circuit (254) when the CTF (128) is in read mode and a servo filter output signal (227) from the servo filter circuit (256) when the CTF (128) is in servo mode. The method includes receiving the analog signal (215) by the input multiplexer (220) and routing the analog signal (215) to the read filter circuit (254) when the CTF (128) is in read mode and routing the analog signal (215) to the servo filter circuit (256) when the CTF (128) is in servo mode.

Abstract: The present invention relates to an information storage apparatus for storing information in a recording medium and to a data transfer method. A particular object of the present invention is to provide an information storage apparatus and a data transfer method, which realize a high-speed transfer of control parameters without deteriorating performance of a control operation. The present invention includes an automatic transfer processing part 102 which transfers control parameters stored in a memory 15 by DMA transfer to an RDC 9, a servo information demodulation circuit 10, a head IC 8, and a DSP 17. The memory 15 is connected to an MCU 101 which controls a read/write operation of a magnetic disk unit 100.

Abstract: Track thinning at an IN point of consecutive recording is prevented by doing a head-track one-edge coincidence tracking by using a head of a larger width than the track width. ATF control means (15) makes a control during reproduction of pre-roll of consecutive recording according to a pilot signal out of the reproduction output from heads (1a, 1c) so that centers of the heads (1a, 1c) may scan the center line of the track. A positioning signal (6g) during the control and a phase of HSW are detected by a detecting circuit (16), and a desired phase having a predetermined advanced amount is set by a desired phase setting means (18) and stored in a storage unit (19). After this, a tracking method switching control unit (23) switches the tracking method into another by which a control unit (20) controls the difference in phase between the positioning signal (6g) and the HSW to a desired value stored in the storage unit (19).

Abstract: A magnetic tape drive has a brake mechanism section which can transfer the state of a reel table from a non-brake state to a brake state by using an electric power that remains after a start of a power failure of a commercial power source. The drive further has a first power failure detecting section which, when a power failure of the commercial power source is detected, transmits a first power failure detection signal; and a controlling section which, when the first power failure detection signal is transmitted in a fast-forwarding state or a rewinding state, transfers the non-brake state of the brake mechanism section to the brake state.

Abstract: A method (and magnetic recording circuit structure) for write drivers to reduce the reversal time for the current through the inductive recording head, includes a write driver output stage providing a write signal output with a write signal source strength SO, a magnetic write head with a write signal input essentially equal to strength SO, and an interconnect circuit having a characteristic impedance ZO coupled to the write signal output of the write driver output stage and the magnetic write head. The write driver output stage preferably includes a source-side termination circuit having output impedance ZS, wherein the source-side termination circuit output impedance ZS is substantially equal to ZO and the source strength SO of the write driver at the input of the interconnect circuit is temporarily enlarged after every polarity reversal of the write signal for a predetermined time duration &Dgr;t.

Abstract: In a substrate structure of a primary disk array apparatus of a disk array system, the primary disk array apparatus contains in one housing at least a plurality of disk drives and a controller substrate with a controller section for controlling the disk drives, and a resource management section that is mounted on the controller substrate of the primary disk array apparatus for managing resources within the housing.

Abstract: There is provided a magnetic tape apparatus which can easily and rapidly restore data and has improved availability. The magnetic tape apparatus includes a plurality of magnetic tape drives, and a control unit for reading and writing information from/in the magnetic tape drives by commands from a host computer. The control unit has a function for storing the same data in the plurality of magnetic tape drives while duplicating the data. The control unit includes a positioning unit for, when the duplicated data is read from one magnetic tape drive to complete the read, performing positioning such that a read position of another magnetic tape drive in which the same data is stored is advanced by a length corresponding to an amount of data read from one magnetic tape drive, and a read continuing unit for continuing read of data from the other magnetic tape drive when data is unsuccessfully read from one magnetic tape drive.

Abstract: A storage apparatus comprises a CPU that provides read/write control of data from/into a magnetic disk, a PLL circuit that generates clock signals having different frequencies, and a selector which selects a clock signal from among the clock signals generated by the PLL circuit according to a control status of the CPU.

Abstract: Methods and systems for controlling a servo are provided. One method includes calculating at least a first switching time to change an amplitude of a command signal to a servo, providing a first amplitude to the servo for the first switching time, and switching the amplitude of the command signal to the servo from the first amplitude to a second amplitude at the first switching time. The second amplitude is the command signal amplitude.

Abstract: A system and method within a hard disk drive for transferring track sector information of a storage disk to a memory device. The system of the present invention includes a disk having multiple tracks, wherein each of the tracks includes at least one sector. The system further includes a memory device for storing sector identification data and user data. A drive data bus is utilized for transferring data between the storage disk and the memory. A controller is utilized to manages read and write operations to and from the storage disk, wherein the controller includes means for selecting either said user data or said sector identification data to be transferred to said memory device.

Abstract: One aspect of the invention is a digital audio tape (DAT) drive having a plurality of read and write heads. Each of the read and write heads has its own parameters, such as a cut-off frequency and a boost value of a read head, a write current of a write head, etc. The parameters of each head are stored in registers and used when an electrical signal representing digital data is to be written to or read from a magnetic tape is processed. When the electrical signal to be written or to have been read by a specific head is processed, the parameters of the specific head will be provided to an equalizer or a pre-amplifier. In the reading process, because the optimum cut-off frequency and boost value are used for a specific read head, the processed electrical signal more accurately represents the digital data recorded on the magnetic tape. In the writing process, the optimum write current to a specific write head makes the write head generate a sufficient magnetic field to magnetize the write head.

Abstract: A circuit (80) and method (84) for protecting read heads (18) of a hard-disk drive system (100). Capacitor C1 is controllably coupled to a dummy head Rdummy during a Vbias mode, so that capacitor C1 has a low, predictable voltage upon returning to Ibias mode, protecting the read heads (18) from damage. The circuit (80) includes logic (82) and algorithm (84) determining when to couple the capacitor C1 to the dummy head Rdummy during a servo bank write (SBW) sequence.

Abstract: The overvoltage applied on a head during switching of the head is prevented. At the time when the head switching signal changes, a switch S4 for turning on/off an operational amplifier Gm1 is turned off, and the operational amplifier Gm1 is turned off. Simultaneously, the switch S3 is turned on, the current source I1 is connected to a capacitor C1, and the capacitor C1 is discharged. Then, switches S1 and S2 for switching the MR head are switched. Finally, the switch S3 is turned off and the switch S4 is turned on, thus the switching of the MR head is finished.

Abstract: A recording target error rate is selected for one or more of data storage devices, and for each data storage device, a dither value is determined for each read/write head in the data storage device, wherein for each head, using a dither value for writing data, essentially provides the selected recording target error for all the heads.

Abstract: There is a need for low-cost and reliable shock-sensing methods in magnetic hard-disk drives to maintain data integrity when a drive is subjected to external shocks. The present invention uses a novel shock-sensing method that is both reliable and low-cost, using a modified head preamplifier to detect servo fields from adjacent disk surfaces, as well as the disk surface being written or read. Servo fields on adjacent surfaces may be staggered. When a write head is writing data to a data field on a disk surface, a read head may be reading a servo field from an adjacent surface, insuring that the write head is on-track. By staggering the servo fields from surface to surface, shock may be sensed by measuring displacement of read heads on adjacent surfaces between servo sectors on the write surface. In addition, the use of a shock sensor or the like may be eliminated, reducing drive component cost.

Abstract: A circuit and method are disclosed for relatively rapidly causing the current flowing through a write head to transition between steady states without generating an appreciable amount of capacitively-coupled noise. Embodiments of the present invention generally provide drive voltage signals to the write head that have no common mode voltage levels during transitions between steady state current levels in the write head. In other words, the drive voltage signals applied to the write head are substantially entirely differential during write head current transitions. In an exemplary embodiment of the present invention, a driver circuit includes switching circuitry connected between the terminals of the write head and reference voltage supplies, such as positive and negative voltage supplies. The driver circuit further includes timing circuitry that generates control signals for controlling the switching circuitry.

Abstract: A hard disk drive for a computer system has at least two actuators for reading data from or writing data to the disks. The actuators may be configured to support the different methods of data access required of them. For example, if large quantities of sequential data are performed, one operation uses both actuators to increase throughput. However, if mostly random operations are to be performed, then independent usage of the actuators is preferred. These two methods of usage can be supported simultaneously, and can even be dictated by the user. The tracking format of the actuators can be configured such that the next logical track is physically located under a head on a different actuator to improve sequential operation. The actuators also may be utilized in a dual-channel configuration so that data can be written to both actuators at the same time, or read back at the same time to improve throughput. In addition, either of these configurations can be selected on a transfer-by-transfer basis by the user.

Abstract: A disk device having access to a disk in different writing modes includes a host PC. The host PC sends a command including a data transfer rate to a controller (disk drive). When the command designating the data transfer rate is received, the writing mode employed for writing data to a disk is automatically switched. The host PC already has the transfer rate to be sent. It is unnecessary to newly prepare a special command to notify the controller in order for switching between the writing modes. Therefore, versatility will not be impaired.

Abstract: Apparatus and method for compensating for position signal distortion during a disc drive seek. A disc drive has first and second data recording surfaces on which tracks are defined, a moveable actuator which supports first and second magneto-resistive heads, and a servo circuit which applies current to an actuator motor to position the heads. During a seek in which the first head is moved from an initial track to a first destination track, upon loss of transduced servo data from the first data recording surface indicative of radial position of the head, the servo circuit switches from the first head to the second head and applies current to the actuator motor to move the second head to a known radial position with respect to the first destination track while transducing servo data from the second data recording surface. The servo circuit subsequently switches back to the first head to position the first head over the first destination track.

Abstract: An offset circuit to correct an offset between differential signals includes a read circuit to read the differential signals, a circuit to measure the offset of the differential signals, and a programmable trim circuit to compensate for the offset of said differential signals.

Abstract: A magnetoresistive element input circuit includes a first resistor connected between a magnetoresistive (MR) element and a first power source. A first current source is connected between the MR element and a second power source and supplies a DC bias current to the MR element in an active mode. A second resistor is connected between the MR element and the first current source. A capacitor is connected to a node between the second resistor and the first current source and to the first power supply. A differential amplifier is connected to the MR element. A voltage supply circuit is connected to the node and supplies the node with a voltage, when the input circuit is in an inactive mode, which is substantially equal to the voltage supplied to the node when the input circuit is in the active mode.

Abstract: A matrix array of recording heads, wherein each head is independent from another both in terms of its magnetic circuit and excitation conductors. Each individual head has a planar magnetic circuit and an helical coil wrapped around the lower part of the magnetic circuit. The matrix array is collectively fabricated using full thin film technology on nonmagnetic substrates. Preferably, the heads are aligned in an oblique lattice with the write gaps aligned along rows and offset by a constant value along columns. Each individual head is connected to the control electronics through interconnects to the backside of the wafer, allowing independent control of the write parameters. The die forming the device is shaped on its edges and top surface to optimize head/medium positioning and minimize wear.

Abstract: A differential circuit to read differential data from a disk by a current bias on a plurality of read heads includes a read circuit to read the differential data from the disk by maintaining the current bias. The current is below a maximum current of a read head having the lowest maximum voltage of said plurality of read heads.

Abstract: An actuator driving method and an actuator driving device for PWM-driving an actuator of a storage disk device are disclosed. This method and device prevent a servo signal from being overlapped with switching noises. The storage disk device includes a head for reading information from a storage disk, a PWM driver for generating a drive current having a pulse width corresponding to a current indication value, a linear driver for generating a drive current of which a magnitude corresponds to the current indication value, an actuator, driven by the drive current, for moving the head, and a control circuit for generating the current indication value for positioning the head from the servo information read by the head from the storage disk. The driving method includes a step of PWM-driving the actuator by the PWM driver, and a step of effecting a switchover from the PWM drive to a linear drive by the linear driver during a period for which the control circuit reads the servo information.

Abstract: A disk drive system including a write circuit for controlling current through a magnetic write head includes an H-switch circuit and a pulse-mode power supply circuit. The H-switch circuit controls direction of current through the magnetic write head. The pulse-mode power supply circuit is connected to the H-switch circuit for providing a higher voltage pulse at a beginning of a switching event of the H-switch circuit to accelerate a change in direction of current through the write head, followed by a lower voltage until a next switching event.

Abstract: A method and apparatus are provided for closed loop control of head load velocity in rotating media mass storage applications. A novel pulsed current velocity controlled head load/unload circuit is provided that uses the back EMF analog signal to modulate pulse amplitude. A system is thus provided having amplitude modulation of a fixed period current pulse train via back EMF feedback, whereby there is no need to monitor back EMF via A/D conversion circuitry.

Abstract: A magnetic disk unit writes, on a magnetic disk, a burst position error data which is used for correcting a positional error of a burst pattern which is used for correcting an error within one track, next to the burst pattern. A write head is controlled a position so as to satisfy a relationship M=N when (N−1)K <WHD<NK, where WHD denotes a core width of a write head, K denotes a pitch of burst boundaries of the burst pattern, and M denotes a number of regions of the burst position error data which need to be provided after the burst pattern. The burst position error data is written on the magnetic disk by the write head the position of which is controlled in this manner.

Abstract: A disk drive recording apparatus includes an actuator arm with first and second heads extending from the actuator arm for writing and reading data to and from a first surface of a disk recording medium. The first and second heads are spaced apart from each other in a circumferential direction along the first surface of the disk recording medium. A switching device switches a data input/output path between the first head and the second head in response to a control signal. A microprocessor identifies a target position on the first surface of the disk recording medium and determines which one of the first and second heads is closer to the target position. The microprocessor then generates the control signal to switch the data input/output path to the first head when the first head is closer to the target position, and generates the control signal to switch the data input/output path to the second head when the second head is closer to the target position.

Abstract: A video signal transmitting apparatus including a reproducing device which reproduces a video signal from a storage medium and has a plurality of channels, a plurality of image display devices for forming a picture according to the video signal, a switching portion for converting a video signal reproduced by the reproducing device to an optical signal and distributing the optical signal to each of the image display devices, a plurality of optical cables for transmitting an optical signal between the switching portion and the image display devices, and a controller for controlling the reproducing device and the switching portion.

Abstract: Because a conventional magnetic head has a structure, in which a MR element and a recording element are stacked, there are cases in which a recording magnetic field affects the MR element, inducing changes in the characteristics of the MR element. An object of the present invention is to lessen the influence of a recording magnetic field on the magnetically sensitive portion of are production element like this, stabilize the performance of the MR element, and enhance the reliability of the magnetic disk drive using a MR element. Further, another object of the present invention is to provide a magnetic disk drive that is capable of improve reliability by using a composite magnet head, which makes a plurality of reproduction elements/reproduction heads correspond to one recording head.

Abstract: A position control system for a magnetic head improves servo tracking characteristics in a low frequency range without impairing the stability of seek operations. The position control system is equipped with two integrators: a first integrator 43 and second integrator 45. The gain K3′ of the second integrator 45 is set larger than the gain K3 of the first integrator 43. The first integrator 43 plays the role of offsetting the bias force acting on the magnetic head while the second integrator 45 plays the role of improving the servo tracking characteristics in the low frequency range.

Abstract: An apparatus and associated method used to control a disc drive having at least one disc and a transducer positionable relative to the disc by a motor. The motor receives energization through at least one power switch integrated on a semiconductor circuit. Temperature of the circuit is sensed proximate the power switch. A temperature signal is provided which is indicative of whether the sensed temperature meets one of a plurality of different threshold temperatures. The power switch is controlled in one of a plurality of different control modes based upon the temperature signal.

Abstract: In an apparatus for recording and reproducing a burst-like digital information signal, a method capable of predicting the time of occurrence of a header indicating the head of the first data of a digital information signal during its reproduction from a recording medium. The digital signal includes a plurality of data blocks each including a header indicative of the head of the block, and each header includes the address of the block. During recording of the digital signal on the recording medium, a plurality of headers which are substantially the same as the headers of the data blocks and including addresses having given relations with the addresses of the data blocks are inserted in a clock regenerating signal recorded before the digital signal for regenerating the clocks for the signal. The headers are inserted at a period equal to the length of each data block so as to be synchronized with the headers of the data blocks.

Abstract: An automation system has a work drive unit (22), in which work programs (14, 16, 18, 20) and work data (15, 17, 19) are stored. It also has a back-up drive unit (12). By means of a back-up program (20), a back-up copy (23, 24) of at least part of the work programs (14, 16, 18,20) and work data (15, 17, 19) can be stored in the back-up drive unit (12). As a result, the part of the work programs (14, 16, 18, 20) and work data (15, 17, 19) can be restored again if required.

Abstract: Comparators receiving reference voltages are provided. An output signal from a differential amplifier is applied to these comparators. Here, the relationship of Vref1>Vref2>Vref3>Vref4>Vref5>Vbias>Vref6>Vref7>Vref8>Vref9>Vref10 is established. The output signals from the comparators are applied to a data latch/threshold level select circuit. The select circuit retains the maximum peak level of the prior comparison by the comparators, and retains the minimum peak value of the prior comparison by the comparators. The select circuit selects the output signal of the comparator of one lower level than the comparator that detects the maximum peak level at the prior comparison to supply the selected signal to a RS flip-flop circuit, and selects the output signal of the comparator of one higher level than the comparator that detects the minimum peak level at the prior comparison to supply the selected signal to the RS flip-flop circuit.

Abstract: A preamplifier integrated circuit for a magnetic storage device includes read channel and a write channel. The read channel includes a filter in a forward signal path which has a low corner frequency (LCF) which varies in a time dependent manner related to the duration of a write-to-read disturbance induced by a transition from a write mode to a read mode. The LCF of the filter moves from a relatively high initial frequency to a lower steady state frequency to effectively reduce the settling time of the write-to-read disturbance without causing read errors which may arise from overfiltering in the steady state. Favorably, the filter in the forward signal path is formed by a unity gain differential emitter-follower in the forward path and a low pass filter (LPF) in a feedback path around the differential emitter-follower, the pole of the LPF being moved to achieved the movement of the LCF in the forward path.

Abstract: A scheme for management of uncertainty in control systems that require adaptation is described. The scheme removes as much uncertainty as possible at design time and manufacturing time by taking advantage of available compute resources in pre-computing a large set of robustness-performance tradeoff based model controllers at different operating conditions for different values of uncertainty parameters that occur in-use and in manufacturing. A group of control models, and corresponding model controllers with an uncertainty bound larger than the best-tuned controller, are generated. A subset of the model controllers is implemented in the system at manufacturing time based on characterization of the system. The subset of model controllers is switched at run time based on transient information received during operation of the system.

Abstract: In an apparatus for reading recorded data, the apparatus, a read signal is sampled from recorded data of a recording medium by synchronizing with a first clock signal. A sample value obtained by the sampling part is stored and also the sample value from the first storing part is retrieved by synchronizing a second clock signal different from the first clock signal and maximum likelihood data is detected by processing the sample value in accordance with a predetermined algorithm. The recorded data is read based on the detected data.

Abstract: Apparatus and method for a head switching operation utilizing an automatic dummy load in a disc drive. A preamplifier circuit sequentially selects head positions and applies corresponding bias currents. A sequence control circuit automatically diverts the path of a first bias current from a head selection circuit to a dummy load after detecting an input of a second head location value into a buffer, and before the input is complete. After a bias current value for the second head is written into the buffer, the sequence control automatically deasserts the path to the dummy load after a predetermined time interval. The second bias current is then applied to the second head.

Abstract: A head suspension assembly for use in a magnetic disk drive includes a magnetic head constituted by a magnetoresistive element for reading data and a head element for writing data, a slider for holding the magnetic head above a surface of a rotating magnetic recording medium, a suspension for supporting the slider, and a head integrated circuit mounted on the suspension. The head integrated circuit having a built-in protection circuit electrically connected with the magnetoresistive element to protect the magnetoresistive element from electrostatic breakdown. Thereby, the magnetic head can be efficiently prevented from suffering electrostatic breakdown due to, e.g., electrostatic discharge occurring during the assembly process of incorporating the head suspension assembly into the magnetic disk drive.

Abstract: The storage device according to the present invention comprises head ICs 1171 and 1172 provided in correspondence to a plurality of magnetic disks 1111 and 111n. When selected, the head IC 1171 outputs a first IC current I1 and the head IC 1172 outputs a second IC current I2. A current/voltage converting circuit 132 converts a synthesized current I0 obtained by synthesizing the first IC current I1 and second IC current I2 to a corresponding IC voltage Vic. A voltage comparing circuit 134 compares a reference voltage Vr to an IC voltage Vic and outputting a result of comparison as a comparison result voltage Vc. A HDC circuit 121C outputs a select command Cs for selecting all IC heads, when a power is turned ON, to the control circuit 125C. The HDC circuit 21C also confirms according to the comparison result voltage Vc whether the number of head ICs is one or two.