Abstract: Apparatus and method for balancing and limiting deflection of a disc of a disc drive. A disc stack comprises a spindle motor hub rotatable about a central axis, a disc mounted to the spindle motor hub, and a circumferentially extending peripheral disc ring affixed to an outermost peripheral surface of the disc. Imbalance of the disc stack is measured, and portions of the peripheral disc ring are removed in relation to the measured imbalance of the disc stack to nominally balance the disc stack. The disc ring protects the disc drive by cushioning contact between the disc and a rigid actuator arm supporting a head adjacent the disc.

Abstract: A method for automatically correcting the dynamic imbalance of a disc pack of a disc drive, the disc pack conveyed to a first selected position in a balance correction assembly station where a rotary positioner lifts and rotates the disc pack to a reference position for the attachment of weighted shims to the disc pack. A shim selector assembly delivers a selected shim, and an end effector transfers the selected shim to a shim attachment assembly. The shim attachment assembly rotates and spreads open the shim so that the disc pack can be receivingly engaged thereby, and the shim attachment assembly releases the selected shim to lockingly engage the disc pack. A flipping assembly reverses the disc pack for placement of another selected shim to the other end of the disc pack, as required.

Abstract: A method for optimizing data transfer performance in a disc drive through selection of optimal reader/writer offsets and write fault thresholds. An initial offset for a selected track is determined as the radial distance between read and write elements of a head as the head is positioned adjacent a selected track. Asymmetric write fault thresholds are selected on opposing sides of the center of the selected track in relation to the ability of the read element to successfully recover data written to the track. An adjustment value is determined in relation to the asymmetry of the write fault thresholds, and the adjustment value is used to modify the initial offset to form a final offset, as well as to make the write fault thresholds symmetric about the center of the track.

Abstract: Apparatus in a disc drive for improving resistance of a disc drive disc stack to radially directed mechanical shocks. A disc is disposed about a rotatable spindle motor hub. Opposing first and second disc support members (such as a disc clamp, disc spacers, or a hub flange) circumferentially extend about the outer hub surface and cooperate to apply a clamping force to the disc to secure the disc relative to the spindle motor hub. The disc support members each comprise a circumferentially extending ring of high friction material having a contact surface that axially extends toward the disc. The clamping force applied to the disc is localized at the rings and at nodes extending from the disc support members so that respective gaps are formed between the disc and remaining portions of the disc support members, thereby reducing radial disc slip, increasing disc dampening, and reducing the likelihood of disc coning and warping.

Abstract: The present invention comprises a method and apparatus for treating a low acid food product. The low acid food product is first acidified to produce an acidified food product and then packaged as the acidified food product. The acidifying step comprises addition of a GRAS acid to adjust the pH to below about 4.5. The acidified food product is then deacidified to return the acidified food product to the low acid food product having a pH above 4.6. The deacidification is accomplished through the addition of an alkaline substance in an amount sufficient to deacidify the acidified food product to a pH of from about 5.8 to about 7.5.

Abstract: Apparatus and method for improving index reference position detection on a disc of a disc drive. The disc includes servo fields used by a servo circuit to control position of a head adjacent the disc and data fields used to store user data, with at least one data field between each successive pair of servo fields. Each servo field includes a binary index field used to indicate angular position. A multi-bit index detection word is selected having at least two bits at a first logical state and at least two bits at a second logical state. A plurality of index fields leading up to, and including a selected index field at the index reference position, are written with respective patterns corresponding to the logical sequence of the index detection word. As the disc rotates, the servo circuit reads each of the successive index fields and identifies the index reference position upon detection of the index detection word.

Abstract: Apparatus and method for writing servo data to a disc of a disc drive. A disc pack comprising a disc and a spindle motor is mounted in a stationary disc servo track writing (STW) fixture, which maintains the disc in a nonrotating, stationary relation while rotating a servo write head around a circumference of the disc to write the servo data to the disc. Once the servo data are written and verified, the disc is removed from the STW fixture and installed into a disc drive. The STW fixture preferably comprises a stationary base portion, top and bottom clamp members which extend from the base portion to hold the disc in the nonrotating, fixed relation, and a rotatable enclosure, adjacent the base portion, which supports the servo write head and rotates with respect to the base portion using air bearings.

Abstract: Method and apparatus for reducing acoustic noise emission in a disc drive assembly. A housing of the disc drive includes first and second plates and side walls which cooperate to form an enclosure for an excitation source disposed within the housing. At least a selected one of the plates has a contact point to which the excitation source is mechanically coupled, a first portion of the selected plate surrounding the contact point and a second portion thereof disposed between the first portion and an outer perimeter of the selected plate, with the second portion having an increased compliance with respect to the first portion. The increased compliance can be formed by reducing the thickness of the second portion. Damping material can be additionally supported by the second portion to provide further acoustic noise reduction.

Abstract: Apparatus and method for improved operational performance of a disc drive by temporarily decreasing disc rotational velocity to reduce self-excited mechanical resonance established within the drive. The disc drive is first initialized by applying current to the spindle motor to accelerate the disc from rest to a nominal operational rotational velocity. Once initialized, the disc drive is operated in a normal mode, as the temperature of the drive increases from an initial, ambient temperature to an equilibrium temperature. During such operation, when the disc drive detects the presence of a self-excited mechanical resonance, the disc drive proceeds to temporarily decrease the rotational velocity of the disc to a reduced velocity to reduce the effects of the self-excited mechanical resonance. Thereafter, the rotational velocity of the disc is restored to the nominal velocity provided the self-excited mechanical resonance is no longer detected.

Abstract: Apparatus and method for a head switching operation utilizing an automatic dummy load in a disc drive. A preamplifier circuit sequentially selects head positions and applies corresponding bias currents. A sequence control circuit automatically diverts the path of a first bias current from a head selection circuit to a dummy load after detecting an input of a second head location value into a buffer, and before the input is complete. After a bias current value for the second head is written into the buffer, the sequence control automatically deasserts the path to the dummy load after a predetermined time interval. The second bias current is then applied to the second head.

Abstract: Method and apparatus for evaluating programming used by a programmable processor device in a disc drive to carry out servo control of a head with respect to a rotatable disc. The programming is first generated as a series of instructions executable by the programmable processor device. Processor emulation software is used to simulate execution of the instructions in a computer. A dynamic model of electrical and mechanical portions of the disc drive is generated using plant simulation software. A dynamic linking program is configured to synchronize and transfer data between the processor emulation software and the plant simulation software. All three programs are thereafter simultaneously executed in the computer to evaluate realtime operation of the programming.

Abstract: The present invention provides a method for the disinfection of seafood. The inventive method includes the steps of (a) preparing a concentrated aqueous solution of a chlorine dioxide liberating compound having a concentration of from about 0.2% to about 25% by weight of the chlorine dioxide liberating compound and having an amount of an acid sufficient to adjust the pH to from about 1.0 to about 5.0; (b) diluting the concentrated aqueous solution to provide a dilute, acidified solution having a concentration of from about 0.00017% to about 0.17% by weight of the chlorine dioxide liberating compound; and (c)contacting the dilute, acidified solution with seafood to disinfect the seafood. Preferably, the chlorine dioxide liberating compound is an alkali metal chlorites, with sodium chlorite and potassium chlorite being particularly preferred. The acid may be any acid generally regarded as safe, as that term is used in the Code of Federal Register, 21 CFR 170.35 and 21 CFR 170.30.

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. During each spin-up of the disc drive, 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. The drive then identifies the configuration of the HDA based on the value of the impedance, initializing the drive accordingly.

Abstract: A rotating impeller pump having an axial face seal carried on a shaft of the impeller positioned inboard of the impeller has a drive mechanism for the shaft carried seal face commonly driven through a keyway in the shaft which drives the impeller such that both the impeller and shaft seal can be easily removed from the shaft.

Abstract: Apparatus for providing nominally laminar flow of air currents in a disc drive. An actuator supports a head adjacent a rotatable disc and includes a rigid actuator arm with opposing planar top and bottom surfaces and a pair of opposing tapered surfaces which taper to a trailing edge. The top, bottom and tapered surfaces define a cross-sectional enclosure to provide nominally laminar flow of air currents adjacent the actuator arm induced by rotation of the disc. A channel is formed in the enclosure by a plurality of adjoining recessed surfaces to at least partially recess a head conductor along the length of the actuator arm within the enclosure to prevent obstruction of the air currents by the conductor. The conductor is preferably a flex circuit with a semi-flexible dielectric layer which supports a plurality of conductive traces.

Abstract: Apparatus and method for simultaneously biasing 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: Apparatus for improving data writing operations to a disc recording surface of a disc drive. A head assembly is supported over the disc recording surface by a flexible suspension assembly of a controllably positionable actuator assembly and includes a write current shaping circuit integrated with a write element. The write current shaping circuit modifies write currents received by the head assembly via a transmission line from a preamplifier driver circuit to remove undesired characteristics from the received write currents. The write element writes data to the disc recording surface using the write currents as modified by the write current shaping circuit.

Abstract: Apparatus and method for compensating for servo data distortion in a disc drive. During a seek wherein a head is moved from an initial track to a destination track on a disc surface, servo position data are decoded on intermediary tracks by generating nominally redundant positive and negative digital pulse streams from positive and negative peaks in a servo readback signal. The positive and negative digital pulse streams are combined using a default Boolean logical operator (such as an AND operator) to qualify pulses in a first output digital pulse stream used to determine head position. When distortion arises that prevents correct detection of head position from the first output digital pulse stream, a second Boolean logical operator (such as an OR operator) is switched in to generate a second output digital pulse stream. Depending on the type of distortion, a selected one of the operators will provide improved servo data decoding.