Abstract: A data recording disk file includes rotatable disks with concentric data tracks thereon. The data disk file includes servo information recorded on at least one of the disks, at least one head for reading the servo information during rotation of the disk, and a voice coil motor (VCM) attached to the head for positioning the head relative to the data tracks. A servo is driven by signals read from the head to control the VCM. The servo includes a processor employing an estimator model for estimating the parameters of the VCM and for generating, from the estimated parameters and the servo information, a digital control signal. The digital control signal is converted to an analog control signal. The control signal is applied to a power amplifier which generates an input current for use by the VCM. The processor provides solely a single estimator model which operates in both saturated mode and linear mode depending on the magnitude of the digital PES.

Abstract: A disk drive motor spindle hub rotatable about a central shaft has a ceramic hub flange attached to a cylindrical hub portion. The ceramic hub flange has a peripherally raised area on which a first disc rests. Additional discs and spacers are alternatively stacked on top of the first disc. The spacers are made of ceramic material with an inner relieved portion. A ceramic clamp washer with peripherally raised area and an inner relieved portion is stacked on top of the first disc. A ceramic clamp washer with a peripherally raised area and an inner relieved portion and a clamp spring in cooperation with the hub flange apply force to hold the first disc and additional discs in place. The clamp force is applied away from the inner diameter of the discs while portions near the inner diameter of the discs are isolated from the hub flange, spacer and the clamp washer.

Abstract: A disc clamp with a varying peripheral wall height at its outermost diameter. Variation of the peripheral wall height results in a circumferentially varying stiffness modulus of the disc clamp at specific circumferential positions relative to the position of multiple mounting screws which attach the central mounting portion of the disc clamp to the spindle motor hub. Varying the stiffness modulus of the disc clamp circumferentially results in even distribution of the clamping force about the contact surface of the disc clamp.

Abstract: A disc mounting system for mounting the discs of a disc drive in a fixed radial relationship to the hub of a spindle motor. The disc mounting system includes a disc mounting ring associated with each disc in the disc stack. The disc mounting ring includes at least one axially extending finger against which a portion of the inner diameter of the disc is brought to bear in an interference fit. In a first embodiment of the invention, the disc mounting ring includes a single finger and that portion of the inner diameter of the disc radially opposite the finger directly contacts the spindle motor hub. In other embodiments of the invention, the disc mounting ring includes a plurality of fingers spaced circumferentially about the ring and the inner diameter of the disc bears on all fingers and has no direct contact with the spindle motor hub.

Abstract: An improved limit stop system for defining the extremes of the range of motion of the actuator of a disc drive. An elongated slot having inner and outer contact surfaces is provided in the bobbin inside the coil of the actuator voice coil motor. A pin member having a compliant portion is assembled through the elongated slot in the coil bobbin and into engagement with stationary components of the disc drive. When the intended extreme of the range of motion of the actuator is reached, either the inner or outer contact surface of the elongated slot contacts the compliant portion of the pin member preventing further motion of the actuator in that direction.

Abstract: An improved inertial latching system for the actuator in a disc drive. The inertial latching system of the present invention includes an unbalanced inertial member which rotates in response to translational or rotational mechanical shocks applied to the disc drive. The inertial member rotates in either a first or second direction, dependent on the direction of the applied mechanical shock, and includes corresponding first and second contact surfaces for engaging a cooperative feature on the moving portion of the actuator. The contact surfaces are configured to act as camming surfaces which compensate for tolerance clearances in the latching system and provide latching power proportional to the amount of applied mechanical shock. The inertial member also includes a centering mechanism for returning the inertial member to a passive rest position in the absence of and at the termination of applied mechanical shocks.

Abstract: An actuator arm bumper for dampening contact between a surface of an actuator arm and a surface of a disc in a disc drive. The actuator arm bumper comprises a non-marring, non-particulating and durable material such as polycarbonate which extends through and beyond the cross-sectional thickness of the actuator arm. The actuator arm bumper is formed from a sphere or rod of polycarbonate material which is placed into an opening of the actuator arm and deformed using a heat staking or crimping operation. A ramp loading installation tool is also used to simultaneously form all of the actuator arm bumpers in the actuator arms of the disc drive.

Abstract: An improved disc clamping system for the elements of the disc stack in a disc drive to increase resistance to radial shifting of the disc stack elements. The increased resistance to radial shifting is achieved by increasing the coefficient of friction between adjacent disc stack elements, and the increase in the coefficient of friction is accomplished by controllably texturing the contact surfaces of various disc stack elements or combinations of disc stack elements. Surface texturing processes particularly suited to specific disc stack elements are disclosed.

Abstract: Method and apparatus for compensating for errors in the location of servo frames in a disc drive, the servo frames providing control inputs to a servo loop of the disc drive. Each servo frame includes an additional compensation field to which a compensation term is written, the compensation term indicative of the average radial error in the location of the servo frame. The compensation term is determined by measuring the radial distance between adjacent servo frames over a plurality of revolutions of the disc and averaging these measured radial distances. The compensation terms are thereafter used in conjunction with position information from the servo frames to control the position of the head. The compensation term facilitates the elimination of repeatable, random errors in the locations of the servo frames, causing the head to nominally follow a circular path about the disc, regardless of the errors in the locations of the servo frames.

Abstract: A low particulating circuit board for a disc drive flex assembly, and a method for forming the same, are disclosed. The circuit board comprises a conductive metal substrate which has sufficient thickness to provide mechanical support and backplane suppression for the circuit board and to efficiently sink heat generated by preamplifier circuitry housed by the circuit board. The substrate has dielectric layers formed on the top and bottom surfaces thereof, the dielectric layers comprising an epoxy interleaved with nonparticulating fibers, such as tetrafluorethylene (TFE) fibers. Traces and pads are provided on the dielectric layers to provide the necessary electrical connections for the preamplifier circuitry. A plurality of circuit boards are formed from a panel and subsequently cut therefrom. Particulate generation is minimized through the use of the metal substrate, as well as recession of the substrate and the solder masks to reduce the amount of material cut during the cutting operation.

Abstract: A disc pack assembly is provided for use within a disc drive having a spindle motor assembly rotatable about a central axis, with a spindle hub and a hub flange. A disc centering sleeve of the current invention with an inner raised portions and outer raised portions is placed around the spindle hub. An information storage disc is stacked on the spindle hub and rests on the hub flange. A disc spacer is placed on top of the information storage disc. A disc clamp is used to secure the information storage disc to the spindle hub. The inner raised portions abut against the outer surface of the spindle hub and the outer raised portions abut against the inner surface of the information storage disc and the disc spacer, centering the information storage disc and the disc spacer concentric with the central axis.

Abstract: A latching mechanism for a disc drive actuator that makes use of a constant force to hold the latch in an unlatched position while the disc drive is in operational mode. The latching mechanism uses the power of the actuator to move the latching mechanism into a latched position under program control or upon the detection of a power loss. While in the latched position, the configuration of the latching mechanism components combined with the frictional contact between heads and discs serves to overcome the constant force and maintain the actuator in its park position, even in the presence of applied mechanical shock, until power is restored to the disc drive. Unlatching of the latching mechanism is accomplished by bringing the spindle motor up to a speed at which the heads begin to fly, eliminating the friction between the heads and discs and allowing the constant force to move the latching mechanism to it unlocked position.

Abstract: Apparatus for clamping a plurality of axially spaced, rotatable elements such as a stack of actuator arms or magnetic storage discs in a disc drive. The rotatable elements are coupled to respective housings for rotation at a respective radius about associated, stationary shafts by bearing assemblies. As used in an actuator assembly, an actuator shaft bearing housing is inserted into an opening in each of the actuator arms and a clamp fastener exerts a clamping force on the actuator arms so as to secure the actuator arms relative to the actuator shaft bearing housing. The clamp fastener comprises a clamp fastener cylinder with an exterior surface which is fixably attached to a corresponding interior surface of the actuator shaft bearing housing. The clamping force is exerted by a clamp disc protruding in a radial direction from the clamp fastener cylinder, beyond the radius of the actuator shaft bearing housing.

Abstract: Apparatus for protecting a disc drive from damage due to non-operational mechanical shocks, the disc drive comprising a rotatable disc having an inner radius and an outer radius and a controllably rotatable actuator adjacent the disc. A snubber is provided adjacent the disc, the snubber having a body portion rigidly affixed with respect to the disc and snubber arms connected to the body portion. The snubber arms extend from the body portion towards the disc and above and below the elevation of the disc, with each snubber arm having a distal end located at a position adjacent the disc between the inner and the outer radii of the disc and towards the outer radius of the disc. The height of each snubber arm limits deflection of the disc at the outer radius of the disc as a result of mechanical shock forced supplied to the disc drive assembly.

Abstract: A disc pack assembly comprises a spindle motor assembly rotatable about a central axis. The spindle motor assembly has a spindle hub, which has at least one ring receiving portion. At least one information storage disc is stacked on the spindle hub and a resilient spacer ring is stacked on top of the information storage disc. A second resilient ring is located in the ring receiving portion of the spindle hub and is adjacent to the inner diameter of the information storage disc.

Abstract: A low sway space disc drive assembly having a base deck with a base portion and side walls extending therefrom. A top cover mates with the side walls to form an internally sealed environment for the disc drive. An external chassis is mounted to the underside of the base portion of the base deck and a vibro-acoustic isolator is disposed between the external chassis and the base portion, the isolator and the chassis providing mechanical isolation for the drive from internal and external vibrations as well as strengthening the base deck. The chassis includes flanges which strengthen the chassis and accommodate a printed circuit board attached to the base deck, the printed circuit board providing the control electronics for the drive. The flanges further include threaded holes for attachment of the chassis to a user environment.

Abstract: A method for following a selected data track on a selected data surface of a disc drive of the type having a dedicated servo system in which guiding of data heads to follow data tracks on data surfaces is effected by positioning an actuator upon which the data heads are mounted in relation to the location of a servo head, also mounted on the actuator, with respect to servo tracks on a dedicated servo surface. The data tracks are organized into cylinders, each containing a servo track, and a selected data track is accessed by seeking to an optimum servo track displaced from the servo track in the cylinder containing the data track by an integral number of track spacings selected to compensate for misalignments greater than a track spacing between the data and servo heads. Data track following is then effected by offsetting the servo head from the optimum servo track to compensate for misalignments of less than a track spacing between the data and servo heads and tracks.

Abstract: Method and apparatus for dynamically compensating for servo burst measurement offsets in a disc drive. A first type of servo position error signal is used during a compensation routine to position a head adjacent a selected track on a disc, the first type of servo position error signal determined from servo burst signals read by the head from servo position fields on the disc. A second type of servo position error signal is also generated from the servo burst signals and the difference between selected values of the second type of servo position error signal is compared to an acceptance limit. Compensation terms are incrementally added to the servo burst signals used to generate the second type of servo position error signal until the difference is below the acceptance limits. Thereafter, the compensation terms are stored and retrieved during normal track following operations to generate a compensated servo position error signal.

Abstract: Method for optimizing parameter values in a read/write channel of a disc drive. A population of error rate points is obtained from selected ranges of a plurality of read/write channel parameters, each error rate point corresponding to a unique combination of parameter values and having an associated error rate value. A weight is determined for each of the error rate points through normalization to the minimum error rate value in the population. A threshold value is determined based upon the error rate values in a plurality of nominally identical disc drives and the weights are compared to the threshold value. Those error rate values having weights less than the threshold are selected and a center of gravity is determined therefrom. At such times that the entire population of error rate values has weights greater than the threshold value, the optimum parameter values are those that map to the center of gravity.

Abstract: A servo track writer used for the writing of servo information to a head disc assembly, the servo track writer including a tuned damper as part of a pusher block assembly, the tuned damper reducing the effects of errors in the written servo information as a result of resonant frequencies induced in the pusher block assembly. The pusher block assembly mechanically advances an actuator of the head disc assembly, the actuator including a head which selectively magnetizes portions of a rotating disc of the head disc assembly to write the servo information. The tuned damper portion of the pusher block assembly comprises a dampening block having a selected mass and a dampening pad comprising a layer of compliant material, the dampening pad isolating the dampening block from the rest of the pusher block assembly. The desired resonant frequency response of the pusher block assembly is achieved through selection of the mass of the dampening block and the compliance of the dampening pad.