Abstract: A load balancing circuit which operates to balance the output voltages of a dual polarity power supply with single polarity voltage regulation. The power supply outputs a positive voltage at a positive voltage with respect to a reference level and a negative voltage with respect to the reference level. The power supply further applies voltage regulation to a selected one of the positive and negative voltages and leaves the remaining one of the positive and negative voltages in an unregulated state. Positive and negative loads are coupled to receive the positive and negative voltages. The load balancing circuit detects a change in impedance of a selected one of the positive and negative loads and applies a corresponding impedance to the power supply to maintain the power supply in a nominally balanced state.

Abstract: A disc drive head positioning apparatus includes a head, a suspension which supports the head, a piezoelectric microactuator which is operatively coupled to the suspension, and a charge feedback driver which is operatively coupled to the piezoelectric microactuator. A method of positioning the head relative to a storage medium is also provided.

Abstract: A load balancing circuit which operates to balance the output voltages of a dual polarity power supply with single polarity voltage regulation. The power supply outputs a positive voltage at a positive voltage with respect to a reference level and a negative voltage with respect to the reference level. The power supply further applies voltage regulation to a selected one of the positive and negative voltages and leaves the remaining one of the positive and negative voltages in an unregulated state. Positive and negative loads are coupled to receive the positive and negative voltages. The load balancing circuit detects a change in impedance of a selected one of the positive and negative loads and applies a corresponding impedance to the power supply to maintain the power supply in a nominally balanced state.

Abstract: An apparatus and method for reducing the number of interconnections in a disc drive through microactuator control and write current signal superpositioning. The disc drive includes a rotatable disc on which a plurality of tracks are defined and an actuator assembly supporting a read/write head having a write element. An actuator motor provides coarse (primary) positional control of the head and a microactuator disposed adjacent the head provides fine (secondary) positional control. A filter circuit is operably coupled between the write element and the microactuator and receives, by way of a common set of conductors, a combined signal comprising high frequency write current signals superimposed upon lower frequency microactuator control signals. The filter circuit filters the combined signal so as to pass the low frequency microactuator control signals to the microactuator and pass the high frequency write current signals to the write element.

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: An inverting power supply (10) having first and second charging capacitors (22, 24) that are alternately connected to a positive power source (12) and a negative output terminal (18) which is to be maintained at a negative voltage with respect to a common ground for the power source and the power supply. Switches (34, 36) connect a positive plate of each charging capacitor to the power supply positive terminal during alternate half cycles of a two-phase clock (20) and charge is bled from the positive plates by switching transistors (46, 50) during the other half cycle to enable charge to be transferred via diodes (52, 54) from the negative output terminal to negative plate of the charging capacitors during the other half cycle.

Abstract: A circuit for enabling the writing of servo data by a servo transducer to a dedicated servo surface of a hard disk drive during the manufacture of the drive while enabling only the reading of servo data at subsequent times that the drive is mated to a computer. The circuit receives power on selected terminals of a connector and includes a level detector that provides a first control signal in response to a power supply voltage level that is below a level selected to exceed voltage levels available from the power supply of a user computer and a second control signal in response to a power supply voltage above the selected level. The second control signal is transmitted to a switch assembly that responds by providing a direct connection between the servo transducer and data terminals of the connector. The first control signal is transmitted to switches by means of which an amplifier, having inputs connected to the transducer and outputs connected to the data terminals, is supplied with electrical power.

Abstract: A method of writing servo patterns to the surface of a disc of a hard disc drive without magnetizing the transducer head by means of which the patterns are written. The surface is initially magnetized in one direction through the transducer head while the disc is rotating to move the disc surface by the transducer head. Each servo pattern is subsequently written by passing a current through the transducer in the opposite direction for selected time interval. Following writing of each pattern, a current is passed through the transducer head in the direction used to initially magnetize the disc for a time interval equal to the time interval during which the pattern was written.

Abstract: Servo disk, including three types of servo patterns distinguishable by phase, are stored in concentric tracks on a magnetic information storage disk. For phase recognition, the pattern types are arranged in triplets of sectors, each sector having a radially extending plurality of only one type of pattern with consecutive patterns in a sector being separated by three track spacings. The patterns are further arranged in radially repeating frames, each including one of each type of pattern, and the patterns are radially offset within a frame by one track spacing from one type of pattern to the next. The patterns have a radial width greater than a track spacing and, in one embodiment, are divided radially into two portions spaced apart by a distance less than one track spacing.

Abstract: Servo data, distinguishable by phase, are stored in concentric servo tracks on a magnetic information storage disk. Each servo track includes a plurality of one type of servo pattern, with consecutive tracks arranged in a repeating sequence of the servo pattern types. For phase recognition, the pattern types further are arranged in a repeating sequence of angular sectors, each sector having a plurality of servo patterns. The servo patterns in a given storage track thus are always angularly offset from the servo patterns in the tracks adjacent thereto, permitting the use of servo patterns radially dimensioned to be greater than the separation distance between adjacent tracks, thereby increasing servo signal reliability and transducer dynamic range.

Abstract: Servo data, including three types of servo patterns distinguishable by phase, are stored in concentric servo tracks on a magnetic information storage disk. Each servo track includes a plurality of only one type of pattern, with consecutive tracks arranged in a repeating sequence of the three servo pattern types. For phase recognition, the pattern types further are arranged in a repeating sequence of angular sectors, each sector having a plurality of but one type of pattern. The servo patterns in a given storage track thus are always angularly offset from the servo patterns in the next adjacent tracks. This permits the use of servo patterns having a radial dimension greater than the separation between adjacent tracks, increasing servo signal reliability and transducer dynamic range.

Abstract: Servo data, including three types of servo patterns distinguishable by phase, are stored in concentric servo tracks on a magnetic information storage disk. Each servo track includes a plurality of only one type of pattern, with consecutive tracks arranged in a repeating sequence of the three servo pattern types. For phase recognition, the pattern types further are arranged in a repeating sequence of angular sectors, each sector having a plurality of but one type of pattern. The servo patterns in a given storage track thus are always angularly offset from the servo patterns in the next adjacent tracks. This permits the use of servo patterns having a radial dimension greater than the separation between adjacent tracks, increasing servo signal reliability and transducer dynamic range.

Abstract: Provided is a circuit for removing an unwanted temporal portion of an incoming signal and for differentiating that signal with respect to a reference voltage level. It includes an input for receiving the incoming signal current through an input capacitor, a differential amplifier for converting input charging current into a voltage with respect to a reference voltage, and a charging capacitor for holding a voltage level representative of the charging current supplied to the differential amplifier during times when the unwanted input signal portion is to be removed from the circuit's output. A current sink and source provides a reset period voltage charge to the input capacitor during times when the unwanted portion is to be removed from the outgoing signal. A switch responds to a reset signal immediately preceding or on the occurrence of the unwanted signal portion.