Abstract: A preamplifier circuit is disclosed comprising a data input for receiving write data, a read signal output for outputting an amplified read signal, a read signal input for receiving a read signal from a read element, and a write signal output for supplying a write signal to a write element. The preamplifier circuit further comprises a first amplifier circuit, responsive to the write data, for generating the write signal supplied to the write element, and a second amplifier circuit for amplifying the read signal from the read element to generate the amplified read signal output via the read signal output. A head control circuit, responsive to head select data, simultaneously enables the first and second amplifier circuits to perform a simultaneous read and write operation.

Abstract: The present invention may be regarded as a self-servo writing disk drive comprising a head having a read element radially offset from a write element. During a first time interval, the read element is positioned over a first radial location to read first A clock data to generate first circumferential timing information and first A servo bursts to generate first position control information. The first position control information is used for positioning the write element over a second radial location, and the first circumferential timing information is used for writing second B clock data and second B servo bursts to the second radial location. During a second time interval, the read element is positioned over the first radial location to read first B clock data to generate second circumferential timing information and first B servo bursts to generate second position control information.

Abstract: The present invention may be regarded as a disk drive with protection against damage due to a thermal asperity. The disk drive comprises a disk having a surface with an asperity, and a magneto-resistive head actuated radially over the surface of the disk for generating a read signal comprising a thermal asperity component caused by the magneto-resistive head contacting the asperity on the surface of the disk. A bias generator is provided for generating an electrical bias applied to the magneto-resistive head, and a thermal asperity detector detects the thermal asperity component in the read signal. When the thermal asperity component is detected, the electrical bias is reduced for a time interval, thereby protecting the magneto-resistive head.

Abstract: A method of calibrating a write current-setting for writing servo sectors onto a recording surface through a head in a head disk assembly of a disk drive is disclosed. A preamplifier circuit has an input for receiving a selected control signal set by a current-setting value, the preamplifier circuit causing current to flow through the head with a current magnitude determined by the current-setting value. A multiple-pass process is performed in which a series of current-setting values are set for the control signal for generating a plurality of quality metrics each indicative of a quality of the selected control signal. Each pass in the multiple-pass process includes the steps of providing a data sequence to the preamplifier circuit to cause a test pattern to be written to the recording surface, and reading the test pattern and generating and storing at least one of the plurality of quality metrics.

Abstract: A disk drive comprising a plurality of recording surfaces and plurality of associated heads is disclosed employing a n-current preamplifier for generating n independently controlled write currents. For example, the n-current preamplifier may be employed during manufacturing of the disk drive to simultaneously write servo sectors to all of the recording surfaces in a “bank servo write” mode. The n-current preamplifier comprises an input for receiving a plurality of current-setting control signals corresponding to the plurality of heads, and a plurality of signal-to-current converters for converting the current-setting control signals into a plurality of write currents for the heads, wherein each write current has a magnitude that is independently controlled by a respective one of the current-setting control signals.