Abstract: A method and apparatus for protecting a disk from overwrites during mechanical shock. If the PES exceeds an off-track threshold for a predetermined number of servo samples, the read/write is suspended for a predetermined duration. The predetermined duration allows for the mechanical shock or disturbance to abate and allows the heads to settle with respect to the track. The off-track threshold being exceeded for several servo samples is used as an indicator of the mechanical force and subsequent undesirable vibration. The writes can then be suspended for the predetermined duration, thereby avoiding overwriting data on adjacent tracks.

Abstract: An apparatus and method are disclosed for generating a low ripple negative voltage suitable for use in a disc drive. A negative voltage supply comprises a pulse generator circuit which generates first and second driver signals in relation to a load of the negative voltage supply. The first driver signal comprises a series of periodically occurring first pulses and the second driver signal comprises a series of periodically occurring second pulses. The first and second pulses are mutually exclusive in time so that at least a minimum delay of selected, nonzero length is provided between transitions of subsequently occurring first and second pulses. The negative voltage supply further comprises a regulator circuit, operably coupled to the pulse generator circuit, which generates the negative voltage in response to the first and second driver signals utilizing a pair of storage capacitors which alternately accumulate and transfer charge to an output capacitor in response to the first and second driver signals.

Abstract: For a read demodulating unit for demodulating read data and servo data which is used for head positioning from a reproduction waveform signal of a magneto-resistive head, a thermal asperity fault detecting unit for setting a predetermined threshold for the reproduction waveform signal and for generating a fault signal when the reproduction waveform signal exceeds the threshold is provided. When a thermal asperity fault is detected by the thermal asperity fault detecting unit, an increase in cut-off frequency of a high pass filter, an automatic gain control lock by an automatic gain control holding circuit, and a phase lock loop lock by a phase lock loop holding circuit are executed in an error avoiding unit.

Abstract: To realize simplification of the structure and high reliability in the disk drive. When a position of a target sector on a disk 2 is detected while skipping data sectors including a first region which is written using a first read/write clock (RDWTCLK) and a second region which is written using a second read/write clock, a controller 5b in a HDC 5 presets to a counter 5a an offset value which is based on the length of a sector to be skipped and a difference in the frequency between the first and the second RDWTCLKs and counts the first RDWTCLK fed from a CLK generator 4d of a channel IC 4 to detect the position of the target sector.

Abstract: A hard disk drive write channel architecture improves the rise-time while utilizing a same supply voltage to provide a boosted voltage, thereby improving the rise-time only when it is needed. The voltage is then connected to the inductive write head through a switch after an appropriate delay, so as to compensate for the delay between the switching of Data line and the peaking of the voltage at the corresponding write terminal. In addition, the same delayed version of the Data line is applied to the inputs of the switching circuit to delay the signal inputs such that the delay timing matches appropriately.

Abstract: A magnetic recording and reproduction apparatus: includes a circuit for changing a reference amplitude value of a Viterbi detector. The circuit is used to record and reproduce data with the reference amplitude value displaced from a reference value, thereby measuring the data error rate. Displacement of the reference amplitude from a reference value increases the data error rate, and therefore the data error rate can be measured within a short time. A data error rate with the reference amplitude equal to a reference value is estimated from the data error rate measurement, thereby making it possible to evaluate the degree of accuracy of a magnetic recording and reproduction apparatus. The data error rate is measured with the reference amplitude of the Viterbi detector displaced from a reference value while changing the equalization coefficient value of a waveform equalizer, the cut-off frequency of a low-pass filter and the write precompensation amount of a write precompensation circuit.

Abstract: A method and apparatus are provided for dual polarity thermal asperity detection in a direct access storage device. A level threshold comparator receives a data signal from a data channel in the direct access storage device and compares sequential data samples of the data signal with a positive level threshold and a negative level threshold. Responsive to each identified consecutive data sample above the positive level threshold and responsive to each identified consecutive data sample less than the negative level threshold, a counter value is incremented. A count comparator compares the counter value with a predefined count threshold and identifies a thermal asperity event responsive to a counter value above the predefined count threshold.

Abstract: A disk drive processing system controls a Servo Timing Mark (STM) detection window in disk drive during a head switch operation. In response to the head switch operation, the system disables a timer that closes the STM detection window during normal operation, and the system tracks the elapsed time from a time point. The system compares the elapsed time to a programmable limit value. The system resumes normal operation if an STM is detected before the elapsed time reaches the programmable limit value and initiates a recovery procedure if the elapsed time reaches the programmable limit value. Advantageously, the programmable limit value can be easily re-programmed if a larger STM detection window is required due to severe STM or head mis-alignment.

Abstract: A magnetic storage system capable of separating thermal signals from data signals is disclosed. The magnetic storage system includes a magnetic media and a head associated with the magnetic media. The head includes a magneto-resistive element which is biased by a modulated bias current. The modulated bias current modulates thermal signals to a first frequency and modulates data signals to at least a second frequency. A method of separating thermal signals from data signals read from a magnetic storage media is also disclosed. The method includes the steps of (1) providing a head for reading information from the magnetic storage media, the head having an MR element; and, (2) biasing the MR element with a modulated bias current.

Abstract: A method and apparatus for writing clock data to a storage medium, such as a disk, is disclosed. The storage medium has tracks on which data are stored. Clock data is written to a present track on the storage medium. The written clock data is read from said present track. Clock data for a subsequent track on the storage medium is generated from the clock data read from said present track. The phase of the generated clock data for the subsequent track is compared with a reference timing signal and the phase of the generated clock data for the subsequent track is adjusted in accordance with said comparison. Said phase adjusted clock data for the subsequent track is written to said subsequent track. Phase errors can be significantly reduced and, for practical purposes, substantially eliminated. It is not necessary to provide a dedicated clock read/write head.

Abstract: A digital signal recording method and apparatus for recording digital signals of two channels along tracks on a magnetic tape in a helical pattern by employing at least two pairs of rotary heads mounted on a rotatable drum oppositely to each other and by making use of a read-after-write function, the paired heads being disposed adjacent to each other. The input signal to be recorded is compressed such that the digital signal recording period for each relevant track is shortened by a ratio corresponding to a time for which a write period for one track and a read period for adjacent one overlap each other. The write period and the read period are thus prevented from overlapping. The reproduced signal for the read-after-write function is prevented from being masked by an input signal recording current.

Abstract: A method, devices, and an article of manufacture for reducing magnetic instability in a magnetoresistive read head of a combined read-write head after writing data onto a magnetic storage medium. The last write pulse polarity that results in the least amount of magnetic instability in the read head is determined, and is referred to as the designated polarity. Then, after a set of write pulses is written, it is determined whether the last write pulse has the designated polarity. If the last write pulse does not have the designated polarity, then an additional write pulse with the designated polarity is written. Thus, the last write pulse before a read always has the designated polarity, thereby reducing the magnetic instability of the read head, and consequently improving read head performance.

Abstract: An H-bridge for applying a current to a coil of a write head assembly for writing data to a magnetic media includes two pair of two switchable transistors. Each pair of transistors is connected between a supply voltage and a reference potential and is adapted to be connected to the coil between the transistors of each pair for turning the transistors turned on and off in a sequence to control the direction of current flow in the coil. The upper transistors of each pair serves a switching transistor, and the lower transistors provide a mirrored referenced current to the coil. A pair of capacitors are connected to a control element of a respective associated one of the lower transistors, and switching circuitry is connected to the capacitors to selectively connect each of the capacitors to inject current into the control element of the respective associated lower transistor when the respective associated lower transistor is turned on.

Abstract: A read signal from a head is amplified by a read amplifier disposed on a head actuator and is fed via a pair of read only transmission paths through an FPC to a control board. The read only transmission paths are provided with a compensation circuit consisting of an inductance and a resistor which are connected in parallel. The compensation circuit compensates for degradation of frequency characteristics of a read signal attributable to stray capacitance of the FPC and to stray capacitance on the control board side.

Abstract: A recording and/or reproducing apparatus for recording and/or reproducing digital audio signal on a recording medium such as a magnetic tape, which includes a recording and/or reproducing unit, an analog-to-digital convertor, a decimation filter, and noise shaper. The recording and/or reproducing unit records and/or reproduces signal on a recording medium at a speed double relative moving speed of a head and the recording medium at least. The analog-to-digital convertor converts input analog audio signal into digital signal with a sampling frequency which is above the audio frequency band, and sufficiently higher than the maximum frequency capable of recording by the recording and/or reproducing unit. The decimation filter reduces the sampling frequency of the digital signal output from the analog-to-digital convertor, and converts it into digital signal of m-bit (m>n).

Abstract: A synchronizing signal detector for a magnetic recording/reproducing apparatus includes a first comparator for comparing a given synchronizing signal pattern with externally input data in a certain bit unit and outputting the number of the same bits in each of comparison unit, a detecting portion for detecting a maximum value of the outputs of the first comparator, and a signal processor for outputting data corresponding to a position where the maximum value from the detecting portion occurs primarily, as a synchronizing signal. In the synchronizing signal detector for a magnetic recording/reproducing apparatus, since the position where the synchronizing signal is generated is detected by comparing the synchronizing signal pattern with the input data, the synchronizing signal detecting error occurs scarcely, thereby improving reliability of the detected synchronizing signal.

Abstract: In a magnetic reproduction apparatus having an MR head, electromigration occurs when a sense current is supplied to the MR head is suppressed, and the service life and reliability of the magnetic reproduction apparatus are improved. Information magnetically recorded on at least one recording medium is read by supplying a sense current to the MR head opposed to the record surface of the recording medium using a current supply circuit, and then decoded by a signal decoder. In the magnetic reproduction apparatus, an MR head information judgment circuit judges whether or not information to be read out from the recording medium by the MR head is needed. Only when the information to be read out by the MR head is needed, does a current supply control circuit allow the current supply circuit to supply the sense current to the MR head. The sense current can be controlled by turning on or off an on-off operation circuit.

Abstract: A method and apparatus for performing head switch operations in a magnetic disk system having a magnetic disk device that is segmented into a plurality of cylinders, which cylinders are grouped into an inner zone, a middle zone, and an outer zone. The inner zone is near the innermost area of the magnetic disk device. The outer zone is near the outermost area of the magnetic disk device. The middle zone is in between the inner zone and the outer zone. The head switch is performed from a current head to a target head. Prior to the head switch, the system determines if the current cylinder is in either the inner zone or the outer zone. When the current cylinder is in either the inner zone or the outer zone, the system seeks the current head to the middle zone, whereupon the system performs a head switch from the current head to the target head. When the current cylinder is not found to be in either the inner zone or the outer zone, i.e.

Abstract: A hard disk drive system (10) includes a read head (21) for reading information from a rotating magnetic disk (12). The read head outputs a servo burst signal in response to servo information (59) on the disk. An analog-to-digital converter (33) is provided to oversample the servo burst signal during each of a plurality of successive time intervals, in order to obtain a plurality of samples for each such time interval. An accumulator (74) is provided to sum the samples for each time interval, in order to obtain for each time interval a respective accumulation value that represents an integration of the burst signal for that time interval. A filtering circuit (86) is provided to determine a burst value for the servo burst signal, by applying a filtering function to a set of the accumulation values. The filtering function may involve determining a median accumulation value from the set of accumulation values, or determining a mean of the accumulation values in the set.

Abstract: A magnetoresistive head achieves maximum signal output with minimal electromigration by using a magnetoresistive element through which a unidirectional sense current is flown. Periodically, a control circuit determines whether one or more switching criteria have been met, and applies a counter-directional compensation current in the magnetoresistive element when the switching criteria are met, thus suppressing electromigration in the magnetoresistive element in the direction of said sense current. In a preferred embodiment, the compensation current is applied during a quiescence period.