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 tolerance ring which provides a low consistent installation force profile as a rotatable member, such as a disc drive actuator, is installed onto a stationary member, such as a shaft extending along an axis. The tolerance ring has a substantially cylindrical base portion from which a plurality of spaced apart raised portions radially extend. Each raised portion has a contact surface with a substantially elliptical cross-sectional shape in a direction parallel to the axis and a pair of transition portions between the contact surface and the base portion. Each transition portion further has a continually radiused cross-sectional shape in a direction parallel to the axis so that, for each raised portion, a selected one of the elliptical cross-sectional shapes and the pair of radiused cross-sectional shapes is convex with respect to the axis and the remaining one of the elliptical cross-sectional shapes and the pair of radiused cross-sectional shapes is concave with respect to the axis.

Abstract: The present invention provides an improved, modular condensate pump assembly that has a collection tank which can be disposed at any convenient location to collect liquid condensate. A removable support plate is supported on the collection tank, and a pump extending into the collection tank is supported by the support plate. A liquid volume control float, also supported by the support plate, communicates with the pump to activate the pump to remove liquid condensate from the collection tank when the condensate liquid reaches a predetermined volume.

Abstract: An apparatus and method for determining the configuration of a disc drive head-disc assembly (HDA). The HDA includes an array of rotatable discs and an actuator adjacent the discs, with the actuator supporting a maximum number of heads in a fully populated configuration and a reduced number of heads in a depopulated configuration. Each head is disposed at a unique head position. A servo circuit determines an impedance of a selected head position having a head when the disc drive is fully populated but not when the disc drive is depopulated. The servo circuit identifies this configuration of the HDA in relation to the determined impedance, and initializes the drive accordingly.

Abstract: An apparatus and method for performing voltage margin testing in an integrated circuit device. The device is provided with an embedded voltage source having a voltage regulator which outputs a regulated analog voltage at a nominal magnitude, such as +3.3 volts. A voltage monitor provides an indication when the regulated analog voltage varies from the nominal magnitude by an output tolerance range determined as a first selected percentage of the nominal magnitude. An adjustment circuit applies a voltage regulator adjustment signal to the voltage regulator to adjust the regulated analog voltage by a second selected percentage of the nominal magnitude. The adjustment circuit further provides a voltage monitor adjustment signal to the voltage monitor to concurrently adjust the output tolerance range to a third selected percentage of the nominal magnitude different from the first selected percentage.

Abstract: A standing seam roof assembly having adjacent roof panels supported by underlying support structure in overlapping edge relationship to form a standing seam between adjacent roof panels, a first roof panel having a female sidelap portion forming male insertion cavities and a second roof panel having a male sidelap portion inserted into the male insertion cavities to form the standing seam assembly. The male sidelap portion has a tang member that lockingly engages a retaining groove of the female sidelap portion. The standing seam assembly prevents unfurling of the first and second roof panels by forming multiple force couples that resist forces due to uplift of the first and second panels. Mastic is placed between portions of the female and male sidelap portions to form a weathertight seal.

Abstract: An apparatus and method for minimizing the effects of rotational vibration upon a disc drive having a base deck supporting a rotatable disc and an actuator having a moveable data head. A fixed head is supported over the disc at a predetermined radius and transduces a circumferentially extending frequency pattern written to the disc at a constant frequency to generate a readback signal. A frequency modulation (FM) demodulator generates a rotational velocity signal indicative of application of rotational vibration to the base deck in relation to changes in frequency of the readback signal. A servo circuit controllably positions the moveable data head in response to the rotational velocity signal and servo information readback by the moveable data head. The servo circuit interrupts a data transfer operation between the moveable data head and a host device when a magnitude of the rotational velocity signal exceeds a predetermined threshold.

Abstract: Apparatus and method for improving operational performance of a disc drive by detecting and compensating for translational vibration modes in a disc drive actuator. The actuator is configured to support a head adjacent a recording disc and pivots about a stationary shaft by way of a cartridge bearing assembly having a pair of ball bearing assemblies. A proximity probe detects translational movement of the actuator assembly relative to the shaft due to, for example, abrupt acceleration and deceleration of the head during a seek operation, or externally applied mechanical shocks. The output of the proximity probe is used to generate a bearing translation signal which is fed into an actuator control servo circuit to modify the amount of current applied to an actuator motor to compensate for the translational vibrations during track following and seek operations.

Abstract: A method of automatically measuring the dynamic imbalance of a disc stack of a disc drive assembly, the disc stack conveyed to a first selected position in a balance measure assembly station where a rotary positioner lifts and rotates the disc stack above a sensor to locate an electrical lead of the disc drive motor. The disc stack is positioned in a reference position to position the electrical leads a for powering the disc drive motor. The disc stack is then conveyed to a second selected position where a motor power assembly clamps and powers the motor and discs. A balance head assembly measures the magnitude and phase angle of the dynamic imbalance of the disc stack and records the measurement to a production control computer.

Abstract: Apparatus and method for dynamically programming the magnitude of read bias and write currents in a disc drive head (30A, 30B). A digital input value is provided to a register (80) of a digital to analog converter (76, 78), the digital input value indicative of the desired magnitude of the head current. A multiplier (82) of the digital to analog converter (76, 78) multiplies the digital input value by a reference voltage to generate an output voltage. The differential voltage between the reference voltage and the output voltage controls the source to drain resistance of a transistor (106) connected in series with a preamp voltage source (114, 120) of a preamp circuit (70). By inputting different digital input values, the source to drain resistance of the transistor (106), and hence the magnitude of the current generated by the preamp voltage source (114, 120), are precisely controlled.

Abstract: A tolerance ring is disclosed which provides increased hoop strength and resistance to deformation. The tolerance ring is placed on a stationary post so as to circumferentially extend about an outer surface of the post. An actuator assembly with an inner bored recess is thereafter placed onto the post so that the tolerance ring is compressed between the surface of the inner bored recess and the outer surface of the post, thereby maintaining a desired nominal position of the actuator assembly about the actuator pivot axis. The mechanical configuration of the tolerance ring includes a substantially cylindrical base portion from which at least one brace portion and a plurality of contact portions project. The brace portion preferably extends along the circumference of the base portion and preferably comprises either a circumferentially extending ridge or flange.

Abstract: An apparatus for reducing manufacturing cost and increasing disc drive actuator assembly stiffness. A post extends from a base deck and supports an actuator assembly and cartridge bearing. In particular, the cartridge bearing comprises a stationary shaft, a bearing supported by the shaft, and a sleeve rotatably supported by the bearing for rotation about the stationary shaft. A first tolerance ring is disposed between an inner surface of the shaft and the post to secure the cartridge bearing in place during assembly. A second tolerance ring is interposed between the cartridge bearing and the E-block to secure the E-block.

Abstract: An apparatus and method for minimizing the effects of rotational vibration upon a disc drive having first and second heads supported adjacent first and second disc recording surfaces, respectively. A frequency modulation (FM) demodulator generates a rotational velocity signal indicative of application of rotational vibration to the base deck in relation to changes in frequency of a readback signal generated from a circumferentially extending frequency pattern written to the first disc recording surface at a constant frequency. A servo circuit controllably positions the first and second heads in response to servo information stored on the second disc recording surface and the rotational velocity signal from the FM demodulator. The servo circuit further interrupts a data transfer operation between the second disc recording surface and a host device when a magnitude of the rotational velocity signal exceeds a predetermined threshold.

Abstract: For low velocity retraction of a disc drive actuator during a parking operation, a system comprising a voltage generator circuit generates a plurality of discrete dc voltage levels, a timing circuit provides a series of timing pulses, and a selection circuit responsive to the voltage generator and timing circuit outputs a voltage profile of increasing voltage steps from the voltage levels and the timing pulses. The voltage profile is provided to a driver circuit that drives a voice coil motor which, in turn, positions the actuator with respect to the discs of the disc drive. The application of the voltage profile during the parking operation causes the driver circuit to act as a voltage source for the voice coil motor. External bias forces upon the actuator tending to force the actuator towards the park position generate a back EMF in the coil, opposing the voltage source of the driver circuit and the motion of the actuator towards the park position.

Abstract: Apparatus and method for clamping discs in a disc stack assembly to provide even distribution of clamping force upon the discs. A teeth lock ring disposed atop a disc stack includes an annular member with a central opening for passing over a spindle motor hub. The teeth lock ring further includes a plurality of grooves and wedge shaped portions alternatively and circumferentially disposed about an inner diameter. Corresponding teeth on the spindle motor hub lock into each of the plurality of grooves. The circumferentially extending wedge shaped portions secure within corresponding grooves on the spindle motor hub. The teeth lock ring effectively compresses a clamp to provide uniform contact between the clamp and a top most disc to prevent disc waviness.

Abstract: An apparatus and method for minimizing the effects of rotational and translational vibrations on a disc drive. A plurality of isolation devices are integrated into a base deck of the disc drive at industry standard locations. Each isolation device includes a rigid threaded collar into which a corresponding fastener is inserted to secure the base to a user environment, a compliant elastomer portion disposed between the collar and remaining portions of the base deck and a rigid stiffener which contacts and surrounds at least a portion of an outer surface of the elastomer portion. Stiffnesses of the elastomer portions are individually selected so that the plurality of isolation devices cooperate to reduce the effects of various translational and rotational vibratory inputs by bunching resonance modes within a selected frequency range.

Abstract: A low inductance electrical spring connector for a disc drive interconnecting the conductors of a flex circuit support and seal apparatus to conductive traces on a PCB, the electrical spring connector having a dielectric housing with a plurality of spaced-apart insulator portions, and a plurality of conductive spring contacts disposed between the insulator portions. The dielectric housing forms an open ended insertion cavity disposable below the flex circuit support and seal apparatus. First ends of the conductive spring contacts are solderable to conductive traces on the PCB, while second ends of the conductive spring contacts are contact surfaces disposed in the insertion cavity . Inserting the conductors of the flex circuit adjacent the contact surfaces into the insertion cavity causes the contact surfaces to engage the conductors of the flex circuit to secure the flex circuit support and seal apparatus while providing electrical contact between the head-disc assembly and the printed circuit board.

Abstract: An apparatus is disclosed for reducing disc deflection in response to the application of a non-operational mechanical shock to a disc drive. The disc drive comprises discs rotatable about a disc axis and each having an outer diameter. A circumferentially extending snubber is provided proximate a substantial portion of the outer diameter of each of the discs. The snubber includes a shroud portion immediately proximate the outer diameter of each disc and snubber arms which extend from the shroud portion in a direction toward the disc axis. The snubber limits deflection of the outer diameter of each disc in response to the application of a nonoperational mechanical shock to the disc drive.