Abstract: A brushless DC motor is started by initially specifying an arbitrary rotor position and applying such drive currents to the three motor phase inputs that the rotor moves to the predetermined position and thereafter applying a current pulse to the appropriate winding to cause the rotor to move in the desired rotational direction. After the motor has begun to turn, the current supply to the motor phase inputs is interrupted. The current in the motor is allowed to decay to a level where the I and R voltage drops in the windings are substantially less than the back EMFs at the speed at which the motor is turning. The small back EMFs generated in the windings are sampled and monitored to detect whether the rotor has moved to a position requiring a change in commutation. Drive current is supplied to the three motor phase inputs in accordance with whether or not a need for a change in commutation was detected by the sample so that the rotor will continue to turn in the required direction.

Abstract: Apparatus and methods are provided for encoding a predefined number of bits of binary data into codewords having a predefined number of bits for a partial-response maximum-liklihood (PRML) data channel in a direct access storage device (DASD). Rate 8/9 block codes having maximum ones and run length constraints (0,8,12,.infin.) and (0,8,6,.infin.) provide timing and gain control and reduced susceptibility to misequalization effects in PRML channels.

Abstract: A laminar flow fan is described comprising a number of fan elements, such as disks, carried on support posts. In a preferred embodiment, each element has a non-circular central aperture. The shape of the aperture provides sufficient clearance for the elements to be placed over the support posts in a first position. Rotation of the elements into a second position with respect to the support posts latches the elements into engagement with the posts, thereby maintaining the elements in this second position.

Abstract: A transducer head skew arrangement used in a multiple disk drive data storage system is provided. The disk drive unit includes a plurality of magnetic disk surfaces mounted for simultaneous rotation about an axis. A first sequence of servo information tracks are arrayed on a dedicated servo disk surface. At least one servo reference track is written on each data disk surface for storing servo reference information. The servo reference track is written on a first data disk surface aligned with a predefined servo information track on the dedicated servo disk surface. Then servo reference tracks are sequentially written on each successive consecutive data disk surface progressively offset radially from the last written servo reference track. A plurality of data information tracks for storing data are disposed at predetermined positions relative to the servo reference track on each the data disk surface.

Abstract: Disclosed is a method for recovering data from a portion of a magnetic surface that contained a read error. After a read error is encountered a magnetic transducer undergoes a head state change. The head state change is accomplished by either writing to a reserve area of the magnetic surface and or reading a portion of the magnetic surface and then rewriting to that portion of the magnetic surface. After the magnetic transducer undergoes a head state change, the portion of the magnetic surface that contained the read error is reread.

Abstract: Engineering changes (EC) for an integrated-circuit (IC) module or circuits connected to an IC module sometimes require the addition of discrete electrical components or circuit chips. Such engineering changes are implemented herein on a small printed circuit card or board that may be physically attached to the top of the IC module. The EC pads on the printed circuit EC card are juxtaposed with the IC module input/output (I/O) pins that require the engineering change. A short fly wire is then soldered between each juxtaposed EC pad and the I/O pin to make the electrical connection between the EC card and the module. In this way, no additional surface area is consumed on the printed circuit board on which the module is mounted.

Abstract: A disk file is presented, having a container (3) for a hub assembly(6) including a stationary spindle (9) attached to the container; a clamp (13) for mounting a disk (11) on a hub (8); bearing means (14, 15), comprising a first bearing (14) located towards one end of the hub (8) and a second bearing (15) located towards the other, for rotatably mounting the hub (8) on the spindle (9); characterized in that the hub assembly (6) further comprises ventilation means (21, 22, 23) for directing an air flow into the hub assembly (6) through the bearing means (14, 15) and out of the hub assembly (6) into the container (3) through a connecting air passage (21) located in the spindle (9) permitting the air to flow through a filter (25). The ventilation means comprises a ventilated spindle (20) having first ventilation ducts (22) extending from the hub assembly into the air passage, and second ventilation ducts (23) extending from the air passage into the container.

Abstract: A method of assembling a disk file comprises merging a pre-assembled actuator assembly and disk stack assembly prior to attaching them to a common base. The relative axial positions of the actuator assembly and disk stack assembly are measured and adjusted to align head arms with collapsed suspensions with the inter disk spaces. Once aligned the two assemblies can be moved together and the heads released.

Abstract: Disclosed is a method and apparatus for attaching a bearing cartridge to an actuator arm assembly in a disk drive. The bearing cartridge includes the actuator shaft, an outer sleeve and a set of bearings. The actuator arm assembly has a bore therein which receives the bearing cartridge. The bearing cartridge is anchored to the actuator arm assembly at a single location.

Abstract: A disk file comprises a head disk enclosure 1 connected to a support frame by a plurality of isolation mounts. Each isolation mount comprises a constrained layer flexure 23 which is rigidly attached at both ends to a bracket 25 of the support frame. Located in an aperture in the constrained layer flexure is a resilient grommet 24. This grommet supports a bolt 27 which passes through the grommet and into the head-disk enclosure casting.

Abstract: A ferromagnetic body is attached or embodied within the actuator arm in a disk drive. The ferromagnetic body is positioned so that the magnets of the voice coil motor attract the ferromagnetic body and produce a force to move the actuator arm so the read/write head attached thereto lands in the landing region of the disk in the event of a power interruption.

Abstract: Disclosed is a method for performing a seek operation in a disk drive using current in the saturation mode to accelerate and decelerate the actuator arm. In a first embodiment, several measurements are made during the acceleration portion of the seek to estimate the deceleration available in saturation mode. In a second embodiment, the point at which the current is switched from acceleration current to deceleration current is adjusted based upon the position where the actuator arm comes within a desired amount of the velocity of a velocity profile assuming worst case conditions.

Abstract: An apparatus and method for determining the difference between two exponents of two floating point numbers is disclosed. The exponent of each number is split into two portions. A high portion contains the most significant bits and a low portion contains the least significant bits. The number of bits in the low portion is related to the number of bits in the fraction portion of each floating point number. To determine differences that require a shift in one of the exponenets, one of the differences between the low portions of the exponents is selected based upon which of several conditions are found with respect to the difference between the high portion. Advantageously, a set of adders which are as wide as the number of bits in the low portion of each exponent are used.

Abstract: A method and apparatus in which the wires from the heads on an actuator arm can be positioned and attached to the arm electronics automatically. A loadspring manufacturing assembly has a pair of wire carrying and positioning tails and a disposable portion. The disposable portion and the wire carrying and positioning tails each have pegs for controlling the position of the wire and for allowing twisting of the wire pairs for purposes of noise suppression. The wires are positioned about the pegs and twisted. The wires are then bonded to the loadspring assembly. A portion of the wire carrying tail has a window or opening therein. The wires are fanned out and spaced apart as they pass across the window. The wire carrying portion also has a living hinge. A portion of the wire carrying tail which includes a latching window which latches a peg is moved about the hinge and positioned at about a right angle to the loadspring. The disposable portion and the unused tail are removed.

Abstract: Disclosed is a disk drive which includes a disk, a spindle motor for rotating the disk, an actuator for moving a transducer over the disk, a pivotably mounted latch for locking the actuator, and a controller for rotating the spindle motor at at least two rates. The latch has two ends. On one end, the latch includes a locking member for engaging a notch in the actuator. On the other end of the latch is a vane for producing a force on the latch caused by the airflow from the rotating disk in the disk drive.

Abstract: A linear actuator for positioning the heads of a disk file relative to tracks on the disks employs a ceramic material having wear properties superior to steel in guide surfaces for guiding a head supporting carriage running on rotary bearings in contact with the guide surfaces. The preferred ceramic material is tetragonally stabilized zirconia.

Abstract: In a disk drive device having multiple disks on a spindle, one of the disks is written with a servo pattern prior to assembly of the servo disk with blank disks into the disk enclosure. The servo pattern consists of a first pattern arranged on each track center along one radial direction of the disk, and a second pattern arranged along the radial direction at each position corresponding to the position of each sector. Servo patterns on each of the disks, including the original servo disk are then written on each of the disks based on the original servo disk. If the disks, when assembled exhibit eccentricity, the second pattern will still be detected, permitting servo writing without complex equipment.

Abstract: A magnetic head/support assembly 10 for assembly into the data access mechanism 70 of a magnetic disk file comprises a magnetic head element 12 and a support structure 11, 20, 21 for the head element. The head/support assembly also comprises a head lead locator 27 including a frame 51 for locating and terminating the leads 15 from the head element 12 remotely from the element. The locator is attached to the support structure and the leads extend across the frame and are retained in fixed spaced apart relationship over a sufficient portion of their lengths to permit direct electrical connection to a correspondingly spaced pattern of conductors on external data channel circuitry carried by the access mechanism.

Abstract: A system for clamping and retaining a stack of rigid magnetic disks is shown using disk spacer rings with an annular groove in the outer cylindrical surface. A concentrated axial load is applied to the stack by support surfaces which overlie the grooved portions of the spacers. The concentrated load is only partially distributed over the radial extent of the spacers with respect to the disks at the axial ends of the stack to resist coning or cupping of such end disks, while the force distribution approaches a uniform loading with respect to inner disks of the stack to retain the undistorted, planar orientation of such inner disks. The grooved spacers also provide a surface which can be used to engage and manipulate the disk assembly during manufacture of the drive.

Abstract: A device that is to be isolated from mechanical shock and vibration such as a magnetic disk storage device is provided with a series of four shock mounting members that have a bolt projecting from one axial end and a stiffened grooved portion at the opposite axial end. A frame member with a rigid end portion and cantilevered, resilient frame members extending therefrom carries a series of U-shaped hook portions that are aligned with the shock mounting members. The pair of hooks on the end portion face the same direction and extend in the opposite direction with respect to the cantilevered frame portions. The other pair of hooks are mounted on the resilient cantilevered frame portions and face toward or away from one another so that they may be placed in engagement with the cooperating shock mounting member grooves by forcing the cantilevered frame portions toward or away from one another and thereafter releasing such parts when the hooks are aligned with the respective grooves.