Abstract: A robust and efficient method for determining the location of a transducer head in a mass storage system. A position-indicative signal characterized by a fundamental frequency F is received from a data path including the transducer head. Energy in the signal at frequencies smaller than F/10 is substantially attenuated by a special filter, which may be an analog or digital differentiator. A sequence of bits indicative of the transducer head position indicator is then extracted from the digitized, filtered signal.

Abstract: An information handling system, such as a disc drive, includes a base, a disc stack rotatably attached to the base, and an actuator assembly movably attached to the base. A region of the disc stack is identified as a parking band, and when power is not provided to the disc drive, the actuator assembly is held in a parked position within the parking band by a magnetic latch. The magnetic latch is overcome during a powerup process by a voice coil motor coupled to the actuator. Other regions of the disc stack are associated with various functions performed by the voice coil motor as the actuator passes over such regions.

Abstract: A method and apparatus for normalizing the acceleration constant used by a servo control system in a disc drive are disclosed. The method and apparatus involve performing a test seek and summing the position error measured at sample periods during the deceleration phase of the test seek. A correction factor applied to the acceleration constant is adjusted if the sum of the position errors differs from the sum of position errors measured from a nominal seek. Adjusting the correction factor to cause a position error sum that is close or equal to the sum from the nominal seek provides a relatively symmetrical seek arrival without additional correction factor offsets or gain variances.

Abstract: An information handling system, such as a disc drive, includes a base, a disc stack rotatably attached to the base, and an actuator assembly movably attached to the base, with multiple movable mill-actuator arms mounted on one portion of the actuator assembly. Attached to an end of the actuator is a voice coil which forms a portion of a voice coil motor. Magnets attached to the base form the other portion of the voice coil motor. A current driver for the voice coil delivers an amount of current to the voice coil to move the actuator assembly. Attached to another end of the actuator assembly is one or more transducers. In order to minimize the disturbance of a seeking milli-actuator, the operation to be executed is to cause the first milli-actuator to return slowly to its rest or zero position. A rate of return control circuit is implemented to drive a milli-actuator such that a milli-actuator at a non-zero or non-rest position will be returned to a rest position at a rate slower than a seeking milli-actuator.

Abstract: The present invention is a method of correcting radial position error signal (PES) values by utilizing predetermined error correction values located at predetermined locations in advance of their associated servo fields. Calculated correction values are written to zero-acceleration path (ZAP) fields on the disc during the manufacture process. ZAP fields are positioned before the servo fields whose PES they are designed to correct. The ZAP field is comprised of two or more correction data elements to correct subsequent PES values. As the read/write head flies along a track, it reads a ZAP field, and stores the PES correction data in local random access memory (RAM). Subsequently, the corresponding servo field is read and the stored PES correction data is used to correct the PES. Two types of ZAP fields are written on the disc—one type for read operations, another type for write operations.

Abstract: A controller generates a control signal that is input into a voice coil motor and causes an actuator to move to a particular position on a storage disk. An actuator model of the actuator is also coupled to the output, of the controller. The actuator model is used to estimate the response of the actuator when a signal is input into the voice coil motor. If some voltage is induced in the voice coil motor by an external vibration or resonance of the actuator, then the voltage output by the actuator will not be equal to the estimated voltage output by the actuator model. The difference of the estimated voltage and the actual voltage output the actuator is input into a resonance controller. The resonance controller then generates a compensation signal that is combined with the control signal to compensate for any actuator resonances.

Abstract: A magnetless rotary actuator for carrying one or more read/write heads across a data bearing medium, the rotary actuator comprising: a stator including a plurality of independently controllable flux generating means for directing flux between the stator and a rotor; the rotor including means for presenting discrete regions of low magnetic reluctance to the controllable flux generating means; torque coupling means for transmitting operative torque from the rotor to the read/write head; and pivot means for supporting the torque coupling means.

Abstract: A method of producing a modified control signal to an actuator arm assembly of a disc drive to reduce RRO includes the step of generating a correction signal corresponding to a position error signal of a current track. Then to determine a high pass filter transfer function of a high pass filter to decrease a gain of an unwanted frequency generated when increasing a learning gain of the correction signal to achieve a faster convergence without any loss of performance in the disc drive. Then to determine filter parameters from the high pass filter transfer function, and to filter the correction signal by passing the correction signal through the high pass filter to generate a modified control signal to the actuator arm assembly of the disc drive using the filtered correction signal to remove the RRO on a next track.

Abstract: A pivot assembly for use with a planar disc drive actuator has bearings which are mounted within the deck of a disc drive. A pivoting shaft is supported by the bearings and extends upwardly, and includes an upper surface for supporting the actuator. A fastener is provided which secures the actuator to the upper surface of the pivot shaft.

Abstract: Disclosed is a magnetic latch for a disc drive. Upper and lower voice coil magnet pole pieces include extensions which bend toward one another, defining a gap therebetween. The gap creates a magnetic field which attracts and holds a disc drive actuator in a park position when the drive is not in use.

Abstract: An actuator with a discrete molded in bumper stop for a disc drive. The actuator has an actuator body moveably supported within the disc drive. A discrete bumper stop has an attaching portion disposed adjacent the actuator body, and an extended portion projecting from the attaching portion engageable with a reference surface of the disc drive at a selected position of the actuator. An overmold member connects the attaching portion of the bumper stop to the actuator body.

Abstract: To alleviate excessive non-repeatable runout (NRRO) on heads between discs, an original multi-disc design is adapted by (a) reducing the number of discs in the stack and (b) configuring the disc drive of the adapted design with a larger nominal inter-disc separation than that of the original design. In one embodiment, the larger separation is maintained by an increased number of disc spacers between each consecutive pair of the discs in the disc stack of the modified design. The result of such a design adaptation is a disc drive with better performance characteristics than would exist by the original design.

Abstract: Method and apparatus for identifying a resonance by changing a spindle speed, which has the effect of changing a corresponding sampling rate and Nyquist frequency. The invention discriminates (1) between plausible frequencies of true resonance and/or (2) aliased resonance from non-aliased resonances. This is accomplished by monitoring whether and/or how a resonance shifts during this speed change. Methods of the present invention monitor resonances by deriving a resonance indicator such as an apparent frequency (below the Nyquist frequency), a gain or error magnitude (compared to a derived threshold at a calculated frequency of interest), or similar criteria tested by values conventionally illustrated on a Bode plot. The present invention further includes steps or structural features for configuring a controller to attenuate or similarly limit an unwanted frequency component of an actuator control signal. In this way, resonances in the actuator can be reduced, and servo speed and accuracy thereby enhanced.

Abstract: A system for hardware intelligent speed monitoring and auto-retract is disclosed. The system contains a monitoring device that monitors the TACH (Tachometer) output of motor driver. The device provides a trigger to the signal processor and a retract mechanism to retract the actuator when the spindle motor speed is unexpectedly much higher or lower than normal speed. The system DSP (Digital Signal Processor) is unaware of such occurrence.

Abstract: According to one embodiment of the present invention, a disc drive includes a disc and a transducer supported by an actuator assembly that is accelerated by controlling current in a voice coil. The disc drive controls a position of the transducer over a present track on the disc in a track-and-follow mode, generates an estimated bias current to be applied to the voice coil to balance a bias on the actuator assembly when the transducer is over the present track, starts a movement of the transducer toward a target track in a seek mode, enters the estimated bias current into a bias table if an immediately preceding movement of the transducer in the seek mode was longer than a seek length boundary such that nonlinear friction in a pivot in the actuator assembly is less substantial, and applies a bias current to the voice coil calculated based on a bias current entry in the bias table during the seek mode.

Abstract: A method, disc drive, and data handling system for optimizing the data writing/transmitting process are disclosed. The disc drive implemented method involves detecting at a current burst whether data written to a previous wedge is recoverable and making the disc drive's buffer space holding that data available for holding other data when the written data is recoverable. The disc drive implemented method also involves detecting at the current burst whether data to be written to a following wedge will encroach upon data written in adjacent tracks and allowing the data to be written in the following wedge when the encroachment is not too severe.

Abstract: An information handling system, such as a disc drive, includes a base, a disc stack rotatably attached to the base, and an actuator assembly movably attached to the base. Attached to one end of the actuator assembly is one or more transducers. Attached to the other end of the actuator is a voice coil which forms a portion of a voice coil motor. Magnets attached to the base form the other portion of the voice coil motor. A current driver for the voice coil delivers an amount of current to the voice coil to move the actuator assembly. A force constant is a multiplier applied to the amplifier so that the output current to the voice coil produces a velocity output replicating the designed velocity output. The force constant is determined during the acceleration phase of the movement of the actuator and transducer. A velocity error signal is produced by comparing the actual velocity of the actuator and transducer to the demand velocity. The error signal can be based on one point in time or over a period of time.

Abstract: An error correction and miscorrection detection apparatus includes a memory buffer for storing user data contained in a data signal. A syndrome computer circuit generates a plurality of EDC syndromes form an EDC codeword. The EDC codeword includes user data encoded with a plurality of m-bit EDC parity symbols. The EDC codeword is encoded with plurality of n-bit ECC parity symbols to form the data signal, such that m>n. An ECC error correction circuit corrects the user data with an error signal generated for each corruption of the data signal. A completion is signal generated once correction of the EDC codeword is complete. A syndrome fix-up circuit is configured to adjust the EDC syndromes based on the received error signals. Once the completion signal is received, a miscorrection by the ECC error correction circuit is detected if a value of the adjusted syndromes is not equal to zero.

Abstract: Disclosed is a disc drive voice coil magnet and spacer arrangement. Voice coil magnets and/or pole pieces are spaced from one another by spacers. On of the spacers is located beyond the coil end of the actuator. This allows the actuator to be lowered into the drive deck in an off-disc position without colliding with the spacer, thereby facilitating in-deck merging of the actuator.

Abstract: A disc drive system and method of screening an actuator resonance includes a servo controller providing a multi-servo zone architecture. The servo controller partitions the disc into a plurality of servo zones. Each of the servo zones has a corresponding servo gain. When an actuator resonance is detected in one of the servo zones, the servo controller reduces the corresponding servo gain of the detected servo zone such that a drive with very low resonance at a certain zone does not affect the servo bandwidth of the other good zones. Accordingly, a drive with very low resonance is prevented from being scrapped. Further, the screening technique allows a drive to have an adequate servo margin for its normal operation after going through a resonance detection test.