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.

Abstract: A method and apparatus for improving baseline recovery of an MR head using a programmable AC coupling pole. The location of the pole may be adjusted to achieve the fastest recovery from a baseline shift without degrading the normal channel performance. Further, the pole may be moved during the data recovery procedure to recover from a data read error. The programmable AC coupling pole includes a circuit path carrying digital data signals read from a recording media by a magnetic head, an amplifier coupled to the circuit path for amplifying the digital data signals, and a recovery time setting device having an programmable recovery time constant associated therewith. Once a data read error has been detected by the system, the recovery time constant may be adjusted to set a recovery time for the amplifier to provide readable data signals.

Abstract: An MR head self-testing method is provided to test for instability in MR heads incorporated with a hard disk drive. A first method is carried out with the disk rotating and includes positioning the MR head over a rotating magnetic storage disk and controlling the MR head to read from erased data fields defined on the disk. This read signal is filtered and conditioned according to preprogrammed filter coefficients contained in an FIR filter to provide an exaggerated read error signal. The exaggerated read error signal is provided to a digital comparator and counter circuit for detecting and counting voltage baseline jumps that exceed preprogrammed positive and/or negative threshold values. The counted positive and negative voltage baseline jumps, which are indicative of MR head instability, are provided to an error diagnostic register for analysis. If the error diagnostic register contains single polarity voltage baseline jumps, the voltage baseline jumps may be caused by thermal asperities on the disk.

Abstract: A recording disk apparatus is provided. The recording disk apparatus includes a recording disk having at least one recording surface with a plurality of spaced recording tracks. The recording disk also includes a positioning arm with a head assembly. The head assembly has a plurality of read transducers. Each consecutive transducer is positioned relative to one another at a distance substantially smaller than a spacing between two consecutive tracks.

Abstract: A reader for interrogating a magnetic tag, e.g. for reading data stored in the tag, is described. The reader comprises a field generating device the magnetic field produced by which defines an interrogation zone, wherein said field generating device comprises: (a) means for generating a magnetic field: (b) a transmit coil for transmitting an interrogating electromagnetic signal into the interrogation zone so as to interact with a magnetic tag, when present in said interrogation zone; and (c) at least one receive coil for receiving an electromagnetic signal generated by a tag in response to said interrogating signal and the magnetic field produced by said magnetic field generating means. The field generating means can take the form of a pair of hollow cylinders, giving rise to a “loop” reader, or it can be a flat magnet, giving rise to a “side pass” reader.

Abstract: Head disc assembly serial number information is encoded in the servo bursts recorded during servo track writing. Specifically, the HDA serial number information is written to the disc during disk manufacture as part of the Servo Track Writing process in between the normal servo frames. The serial number is preferably written on preexisting unique system (non-user) tracks in-between normal servo frames. The encoded serial number can be retrieved by increasing the sampling interval of the servo information, i.e., by over-sampling the servo information. More specifically, by writing the serial number in a servo burst exactly in the middle of two normal servo frames, the information can be retrieved by 2× over-sampling routines called by system diagnostic routines or disc drive certification routines. In addition, a disc drive apparatus having a retrievable encoded head disc assembly serial number is provided.

Abstract: An improved write drive circuit which provides an adjustable writer drive current and overshoot transient for a H-bridge drive circuit in a hard disk drive. The invention uses a variable capacitor circuit to give an initial boost to the write driver transistors. In a preferred embodiment, the capacitance of the variable capacitor is controlled by a word written to the disk drive pre-amp over the serial control port.

Abstract: Magnetoresistive, MR, heads and giant magnetoresistive, GMR, heads are used in hard disk drive storage systems. The heads have a pinned layer whose magnetic orientation, if incorrect, gives rise to data read errors. A pinned layer reset method and circuit is provided to restore the magnetic orientation of the pinned layer by applying a reset pulse to the MR head. The circuit employs the existing low frequency cutoff capacitor in the initial amplification stage of the preamplifier to charge the magnitude of the reset pulse. The magnitude of the pulse is programmable by selecting bits in the existing write current digital to analog converter. The head select input transistor applies the pulse to the MR head. The pulse width is programmable as is the discharge rate. The settling value of the pulse is determined by the existing read current digital to analog converter value.

Abstract: An apparatus and method for evaluating surface characteristics of a recording disc prior to incorporation into a disc drive. A glide test system includes a glide test head supportable over the disc, the glide test head having a negative-pressure air bearing slider and a contact sensor which outputs a signal when the glide test head contacts a feature of the disc surface. The glide test head and the disc are characterized as opposing plates of a variable capacitor with a dielectric layer therebetween including at least a layer of air supporting the glide test head. A voltage source, operably coupled to the glide test head and the disc, applies a fly height control voltage across the capacitor to adjust the fly height of the glide test head. The disc surface preferably comprises a data region configured to magnetically store data as the disc is rotated and a texturized landing zone configured to support the disc drive read/write head when the disc is stopped.

Abstract: The present invention relates to circuitry for processing an analog read signal, such as a signal produced by a magnetoresistive head, in a magnetic data storage system. The circuitry processes the analog signal before the signal reaches the detector which converts the analog signal into a digital signal representative of the data originally stored on the magnetic medium. In one embodiment, the invention comprises circuitry for equalizing the amplitudes of the positive and negative pulses in the analog read signal. In another embodiment, the invention comprises circuitry for reducing the baseline shift of the analog read signal. The invention may be used in magnetic data storage systems using any conventional data detection method.

Abstract: Apparatus and method for simultaneously biasing multiple magneto-resistive read elements in a disc drive head/disc assembly. A preamplifier circuit sequentially applies read bias currents to successive pairs of heads of the head/disc assembly, wherein the read bias current applied to a selected one of each pair of the heads is used to transduce the servo data from the associated disc recording surface, and the read bias current applied to the remaining one of each pair of the heads is used to prepare the remaining one of each pair of the heads to subsequently transduce the servo data from the associated disc recording surface. The preamplifier circuit includes at least first and second read bias current sources and a head selection circuit.

Abstract: A rotary magnetic head apparatus is provided which can be formed into a small size even if a plurality of reproduction heads are provided.

Abstract: A disk medium includes a substrate and a designed topography of individually magnetizable features formed on the surface of the substrate. At least a portion of the disk topography is formed from an etched layer of magnetizable material deposited on the surface of the substrate. An information storing and retrieving system records information on the disk medium magnetically and reads the recorded information optically or magnetically. The information stored in the disk is of the form of bits each represented by a magnetic field established in the features. The direction of the magnetic field can be in a direction other than the bitstream direction, with the magnetic storing and retrieving system having a pair of non-parallel heads adapted to recognize this direction as representative of discrete logic levels formulating the basis of a non-binary storage system having significantly increased storage density.

Abstract: A system and method for AC erasing fields on tracks in a disk is provided. An AC three-pass write technique is used in a disk drive to erase old data from an older generation, wide track disk with a newer generation, narrower read/write head, and write new data to the wide track disk with the narrower head. A strong AC bias field (instead of a DC bias field) is applied to the read/write head during the erase passes in the multipass technique, thereby reducing the net signal-to-noise ratio when the written data is read back in an older drive with a wider head. Moreover, a request from a disk drive controller for a DC erase is detected and the DC erase signal is automatically replaced with an AC erase signal.

Abstract: A magnetic recording medium wherein, when the axis of easy magnetization of the magnetic recording medium for magnetically recording information by means of a magnetic head is projected onto a surface of the magnetic recording medium, the axis projected onto the surface of the magnetic recording medium exists so as to be unidirectionally inclined with respect to the direction of a track on which information is to be recorded, whereby, by using the magnetic recording medium, there can be provided a magnetic head and a magnetic read-write apparatus greatly improved in longitudinal recording density.

Abstract: Apparatus for improving data writing operations to a disc recording surface of a disc drive. A head assembly is supported over the disc recording surface by a flexible suspension assembly of a controllably positionable actuator assembly and includes a write current shaping circuit integrated with a write element. The write current shaping circuit modifies write currents received by the head assembly via a transmission line from a preamplifier driver circuit to remove undesired characteristics from the received write currents. The write element writes data to the disc recording surface using the write currents as modified by the write current shaping circuit.

Abstract: A magnetic tape unit includes a magnetic tape, a magnetic head, a phase-locked loop (PLL) and a desynchronized track detector. The magnetic tape is provided with a plurality of tracks. The magnetic head is arranged to simultaneously read out data from the tracks on the tape. The PLL is arranged to perform bit synchronization of data read out from each of the tracks on the tape. The detector is arranged to detect a desynchronized track by comparing transmission speeds of data read out from the respective tracks on the tape.

Abstract: A track format is prescribed so that an ST-AFN indicating the AFN of the streaming start position be written on each track, and at the time of reference value measurement, an append point is detected by monitoring coincidence between the AFT and the ST-AFN on the scanned track. And, on the basis of the detected append point, a reference value is measured for each streaming recorded area, and this reference value is held matched with the recording positional information of the streaming recorded area.

Abstract: Apparatus and method for servo writing with simultaneous biasing of multiple magneto-resistive read elements in a disc drive head/disc assembly. A preamplifier circuit sequentially applies read bias currents to successive pairs of heads of the head/disc assembly, wherein the read bias current applied to a selected one of each pair of the heads is used to transduce the servo data from the associated disc recording surface, and the read bias current applied to the remaining one of each pair of the heads is used to prepare the remaining one of each pair of the heads to subsequently transduce the servo data from the associated disc recording surface. The preamplifier circuit includes at least first and second read bias current sources and a head selection circuit.

Abstract: A servo burst signal recording method using an enhanced pattern and a disk recording medium are provided. The disk recording medium having at least two servo burst regions on which servo burst signals are recorded in the diametrical direction on tracks of the disk recording medium, the servo burst regions each being divided into at least two sub-regions in a traveling direction of a head, one sub-region having the same width as that of a track, and the other sub-region having a smaller width than that of the track. The disk recording medium enables the user to obtain a servo burst signal component without having a dead zone even in the case when the width of a reading head is smaller than that of the recording head, which enhances the accuracy of the tracking control.