Seagate Technology Incorporated

Joseph C Liu

Zine-Eddine Boutaghou

Dallas W Meyer

Xiong Liu

Kevin Arthur Gomez

Myint Ngwe

MingZhong Ding

Mark James Schaenzer

Lowell James Berg

ChoonKiat Lim

Choon Kiat Lim

Wai Onn Chee

Kok Tong Soh

Andre Y Liem

Paul E Kupinski

Sen Chai Khew

Alan Choon Tan

A method and apparatus are provided for generating an adaptive feedforward cancellation signal for a next sector of a disc in a disc drive. The cancellation signal includes at least one tap weight multiplied by at least one trigonometric function. To form the cancellation signal, the method and apparatus first determine a servo loop transfer function relative to a feedforward cancellation component in the disc drive. The transfer function is then inverted to form filter parameters. A position error value is then measured for a current signal and is passed through a filter formed from the filter parameters. This creates a filtered position error value that is used with the tap weights of a current sector to determine the tap weights for the cancellation signal of the next sector.

Method and apparatus for adaptive feedforward cancellation

Embodiments of apparatus are directed to a rotational shock tester system comprising a disc drive support system, a drop mechanism and an impact apparatus. The disc drive support system includes a rotation plate, wherein a disc drive is coupled to the rotation plate. The drop mechanism is coupled to the disc drive support system and includes an elevating apparatus, wherein the elevating apparatus elevates and releases the rotation plate which is supporting the disc drive. The impact apparatus is releasably coupled to the drop mechanism and is aligned with the rotation plate such that upon release of the rotation plate, the rotation plate impacts the impact apparatus such that the impact apparatus imparts an angular acceleration to the rotation plate and imparts a rotational shock to the disc drive.

Rotational shock tester apparatus

Apparatus and method for mounting a disc drive with vertical and horizontal compressible elements and for stabilizing the disc drive during use. Shock mounts are affixed to a horizontal surface (i.e. parallel to a data surface) of the disc drive, slowing vertical shock pulses transmitted from the frame to the disc drive. Recessed vertical surfaces are formed on sides of the housing to accommodate additional dampeners, which slow horizontal shock pulses while reducing operating vibration.

Mounting frame using an operating vibration damper at a recessed side

Gimbal micropositioning device

An apparatus for measuring magnetic recording head transducer to disc surface spacing and a method of fabricating the same are disclosed. A slider body of a read/write head has first and second rails forming portions of an air bearing surface of the slider body. First and second cavities are formed in the first and second rails of the slider body at the air bearing surface. First and second capacitance plates are positioned within the first and second cavities, respectively, such that a surface of each of the first and second capacitance plates is substantially coplanar with at least portions of the air bearing surface.

Capacitance probe for magnetic recording head transducer to disc surface

A method and apparatus for detecting and measuring head-disc interference, in a disc drive, for the purpose of taking preventative and corrective measures, to prevent disastrous head crashes and permanent data loss, is disclosed. The method and apparatus detect and measure the frequency modulation (FM) of a read back signal generated by longitudinal head oscillation, as a result of head-disc interference. The longitudinal head oscillation can be ascribed to the non-linear response of the air bearing supporting the head on the disk surface. The response exhibits a vibration frequency in the head in the 100 to 250 kHz range. The more severe the interference contact is, the higher the vibration amplitude which then leads to read signal frequency modulation (FM). A method and apparatus is described to detect the FM modulation and thereby to detect the severity of the head disk interference for proximity recording. A pre-written pattern on the disk can be read back to monitor for FM, and a modulation index, .beta., is generated by observing the resulting signal. By demodulating the modulated read back signal, the severity of the interference can be determined. This method can be applied as a diagnostic tool at a manufacturing test station, in a laboratory test setup, or in a disk drive using the disk drive's own read/write channel electronics, without the need for an external sensor.

Detection and measurement of head disc interference using read back

A device for reading and recording magnetic data includes an aerodynamically supported slider with an air bearing surface, and a transducer mounted to the slider for movement toward and away from the air bearing surface responsive to changes in the slider operating temperature. In one embodiment, the transducer movement is primarily due to a difference in thermal expansion coefficients between a transducing region of the slider incorporating the transducer, and the remainder of the slider body. In another embodiment, a strip of thermally expansive material is incorporated into the slider near the transducer to contribute to the displacement by its own expansion. A temperature control circuit, coupled to the strip of thermally expansive material or to a resistance heating element on the slider, employs a variable current source to control the slider temperature and transducer displacement. Nominal slider operating temperatures can be set to achieve a predetermined transducer flying height, to compensate for variations in flying heights among batch fabricated sliders. Optionally, a temperature sensor can be employed to measure the slider operating temperatures and provide a temperature sensitive input to the temperature control circuit.

Slider with temperature responsive transducer positioning

A gimbal for supporting a slider at its leading surface in a disc drive assembly includes a gimbal body, a slider support beam and a slider mounting tab. The slider support beam is carried by the gimbal body and defines a vertical slider alignment feature. The slider mounting tab extends out of plane from the slider support beam and defines a horizontal slider alignment feature. The slider mounting tab is attached to the leading surface of the slider. The design of the slider mounting tab of the present invention is useful for supporting a leading edge microactuator at a leading edge of the slider for micropositioning a transducer over ideal track centers on a disc surface.

Gimbal suspension for supporting a head in a disc drive assembly

An swage plate bumper overlies the swage plate of a suspension arm and the end of an actuator arm in a computer disc drive. The swage plate bumper may be molded in two pieces which snap together onto the actuator arm through the swaged hole. Alternatively, the swage plate bumper may be provided with an adhesive attachment to the swage plate, or the swage plate may be coated with a compressible coating during manufacture. The swage plate bumper extends over four corners of the swage plate and prevents damage to the disc surface which might otherwise be caused when the corners of the swage plate contact the disc during a drop or other sudden acceleration.

Swage plate bumper for disc drive

A formation process has a plurality of process steps performed according to a set of process parameters. The formation process is used to form substrates in magnetic discs. A displacement signal is obtained which is representative of surface displacement of the substrate after at least one of the process steps. A first spectral signature is determined based on the displacement signal. The first spectral signature has characteristics representative of the surface displacement of the substrate when processed according to a first set of process parameters. The first spectral signature is compared with a second spectral signature having characteristics indicative of surface displacement of a substrate when processed according to a second set of process parameters. Based on the comparison, the set of process parameters is identified which provides a spectral signature closest to a desired spectral signature.

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Singapore, Singapore

Joseph C Liu