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 signal processing apparatus in which a signal is processed using a partial response method is provided. The apparatus includes a signal processing unit which performs an operation (1−D) on each bit of an input code, where D indicates a delay of one bit; an equalizing unit which equalizes a bit sequence processed by the signal processing unit to a Nyquist characteristic; and a maximum likelihood detection unit which detects a maximum likelihood bit sequence from the bit sequence equalized by the equalizing unit. The input code of the signal processing unit is a 1/7-conversion RLL code of input data.

Abstract: Methods and systems for detecting and correcting for undesirable vibrations impacting the servo systems in data storage devices. A detection technique is provided wherein a detection filter is configured to scan a position signal of the servo system across a range of frequencies, and, at each respective scanned frequency, record an amplitude associated therewith. The recorded amplitudes are examined to determine whether any exceed a threshold, thereby locating a peak frequency of the vibration. Using the detected peak frequency of the vibration, a corrective filter is configured to operate about the peak frequency of vibration, thereby reducing its impact on the position signal in the servo system.

Abstract: A time counting device, a cache memory and a copy control circuit are added to a conventional disk drive so that recorded information is copied periodically and automatically. Alternatively, a cache memory, a copy control circuit, a reference control circuit, a first time counting device and a second time counting device are added to the conventional disk drive so that information which remains recorded for a predetermined period of time after its last recording date is automatically copied. According to another embodiment, a reference signal is recorded in advance and a reproduced output is periodically measured. If the reproduced output is lower than a reference value, recorded information is automatically copied. Other embodiments are also disclosed with the aim of ensuring that information recorded on a magnetic media can always be reproduced reliably, even in the case of high density recording.

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 precompensation 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: A disk drive is disclosed comprising a disk having a plurality of tracks including a plurality of data tracks and a plurality of reserved tracks. A plurality of embedded servo sectors are dispersed circumferentially around the tracks, the tracks are banded together to form a plurality of zones, each data track comprises a plurality of data sectors each having a first number of bits for storing user data, and each reserved track comprises calibration sectors each having a second number of bits for storing a calibration test pattern, wherein the second number of bits is greater than the first number of bits.

Abstract: A preamplifier system includes an amplifier stage having at least one feedback network. The feedback network has a feedback resistance that may be adjusted to improve a frequency response of the preamplifier. A feedback control system is operative to set the resistance of the feedback network as a function of a resistance value of an associated read/write head.

Abstract: In hard disk drives (HDD), a magnetic read head moves over a portion of the hard disk when reading data. A preamplifier, having an initial amplification stage of the single ended type, connects to the magnetic read head and amplifies a data signal picked up by the magnetic read head. The preamplifier typically has multiple read heads, or channels. In order to reduce noise coming into the read channels of the preamplifier from the substrate capacitances of the input transistors connected to the read heads, the input transistors are grouped together into multiple banks that are multiplexed, or turn on separately. To further aid noise reduction, the poles of the single ended amplifier are matched, that is, the frequency response of the constant voltage side is matched to the frequency response to the signal side. This effectively reduces both ground noise and Vcc power supply noise as the the noise becomes common mode on the inputs to a differential amplifier that is connected to the single ended amplifier.

Abstract: An actuator arm assembly is provided in a disc drive. The disc drive includes a disc with a surface for storing information and a first actuator for moving the actuator arm assembly relative to the surface of the disc. The actuator arm assembly includes an actuator arm coupled to the first actuator, a load beam coupled to the actuator arm, a suspension coupled to the load beam and an air bearing coupled to the suspension. A transducer is mounted on the air bearing and positioned to access the surface of the disc. A second actuator is coupled to the air bearing and the load beam and is controllable to move the air bearing relative to the surface of the disc and relative to the load beam.

Abstract: A recording medium comprising a data-recording surface is formed of plural tracks, with a respective track having a data section in which units of data are to be recorded. Only one header section is provided before the data section, the header section serving as a reference position for dividing said track into sectors. The header section is defined by prepits formed in the data-recording surface. As a result, data is recorded in the header section at such a high density that the header data is reproduced with super resolution.

Abstract: The invention provides a write driver circuit for writing an information signal on a magnetic record carrier. The write driver circuit comprises a first and a second input terminal (20,22) for receiving the information signal. A first current sink (24) is available, having a first transistor (T3) of a first type, having a first main electrode coupled to the first point of constant potential (+), having a second main electrode coupled to the first input (34) of a write head combination (32) via a first impedance (38), and a control electrode coupled to the first input terminal (20). A second current sink (28) is available having a second transistor (T4) of the first type, having a first main electrode coupled to the first point of constant potential (+), having a second main electrode coupled to the second input (36) of the write head combination via a second impedance (42), and a control electrode coupled to the second input terminal (22).

Abstract: A differential circuit to read differential data from a disk by a voltage bias includes a read circuit to read the differential data from the disk by maintaining the voltage bias and a feedback circuit to sense deviations in the voltage and to adjust the voltage in response to the deviations.

Abstract: An apparatus and method are disclosed for minimizing damage to a disc drive during head switching operations. The disc drive comprises a plurality of magnetic recording surfaces to and from which data are transferred using read/write heads, each head utilizing the application of a bias current during operation. To switch from a presently selected head to a target head, the disc drive determines a first value indicative of the magnitude of a bias current for the presently selected head and a target bias current to be applied to the target head. When the second value is greater than the first value, the disc drive switches from the presently selected head to the target head and then applies the target bias current; conversely, when the first value is greater than the second value, the target bias current is applied to the presently selected head and then the disc drive switches from the presently selected head to the target head.

Abstract: A technique for converting asymmetric waveforms into symmetric ones. The technique is used in disk drive read channels which receive asymmetric waveforms from magnetoresistive heads. Conversion of these waveforms into symmetric ones results in improved bit error rate of the read channel. The correction technique can be used for any general asymmetry transfer function, and in any general application where the correction of asymmetric waveforms is needed. The technique involves splitting the input signal into two rectified paths and applying correction independently on each of the paths.

Abstract: A magnetic disk for a magnetic recording/reproduction device includes a magnetic head, wherein a magnetization bit-pattern corresponding to a preformat information signal is recorded beforehand on the magnetic disk, wherein the magnetization bit-pattern is recorded by contacting a surface of the magnetic disk with a surface of a master information carrier having a pattern corresponding to the preformat information signal, and a portion of the magnetization bit-pattern corresponding to at least one signal selected from a clock signal and a synchronous signal has a recording width that is larger than a recording track width of the magnetic head in a radial direction of the magnetic disk.

Abstract: A method of mounting a volume from a tape medium on a tape drive apparatus. The method reads a bar-code indicating the volume from a tape cartridge, attaches the tape cartridge to a tape drive, and detects the current track position on the basis of a longitudinal track. The method then determines whether a beginning volume label or a last used area volume label is nearer to the current track position, reads the nearer volume label from the tape medium, confirms the volume by comparing the nearer volume label with the bar-code, and mounts the volume onto the tape drive.

Abstract: A disc-like record carrier has a machine-readable information track in which is provided record carrier control information including the actual physical diameter of the carrier.

Abstract: In a magnetic disk apparatus in which heads integrally having write heads and read heads are arranged correspondingly to data surfaces of plural media, servo information including phase servo patterns is written discretely in a track direction onto the data surfaces of the plural media. For this reason, at first, displacement amounts of the read heads with respect to the write heads are measured in each head and each cylinder position of the media. Next, phases of the phase servo patterns are adjusted so that relative displacement amounts between the reads heads are eliminated in each head and each cylinder position of the media, and the phase servo patterns are written.

Abstract: An analog-to-digital converter 16 includes first and second analog-to-digital converters 22 and 24 both of which receive an input signal. The first analog-to-digital converter 22 is configured to be centered around a first signal level point while the second analog-to-digital converter 24 is configured to be centered around a second signal level point. A decoder 26 receives inputs from the two analog-to-digital converters 22 and 24 and selects between the first analog-to-digital converter 22 output and the second analog-to-digital converter 24 output.

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.