Abstract: A hard disk drive (HDD) detects and measures external stray magnetic fields with existing HDD components. After detecting a strong external magnetic field, read and write operations of the HDD are suspended, and/or other proper corrective actions are taken to minimize loss of data. To measure the stray magnetic field, the magnetic head reader is used as a field sensor. The resistance of the reader changes in the presence of the field, such as with the preamp in the HDD. The resistance also changes with temperature. If the temperature inside the HDD is measured, the resistance change due to temperature is normalized. Even without being able to measure the HDD temperature, the stray magnetic field can be measured with a top head and a bottom head in the HDD. The temperature sensitivity of the reader is thereby cancelled out.

Abstract: A method and apparatus for optimizing data record quality on a disk for a pair of read and write heads, in which the write head is bigger, by adaptively varying linear and track density of overlapping recorded tracks to achieve a target storage capacity. In the method, target storage capacity and radial writing direction are selected. Read and write widths of heads are determined. A linear density and offset distance pairing for optimizing record quality at target storage capacity is determined, wherein offset distance is less than write width but greater than read width. The write head writes a track at the linear density, is offset in the radial direction by the offset distance, and the offset distance is stored. The write head writes a new track at the linear density. Offsetting, storing offset, and writing a new track are repeated until desired data is written into a cluster.

Abstract: A method and apparatus for optimizing data record quality on a disk for a pair of read and write heads, in which the write head is bigger, by adaptively varying linear and track density of overlapping recorded tracks to achieve a target storage capacity. In the method, target storage capacity and radial writing direction are selected. Read and write widths of heads are determined. A linear density and offset distance pairing for optimizing record quality at target storage capacity is determined, wherein offset distance is less than write width but greater than read width. The write head writes a track at the linear density, is offset in the radial direction by the offset distance, and the offset distance is stored. The write head writes a new track at the linear density. Offsetting, storing offset, and writing a new track are repeated until desired data is written into a cluster.

Abstract: A magnetic head includes a magnetic write structure having a first magnetic layer having a first pole, a second magnetic layer having a second pole spaced apart from the first pole, and a third magnetic layer having a third pole contacting the second pole. The third pole has a third-pole width greater than a second-pole width. An inductive coil positioned adjacent to the third magnetic layer controllably magnetizes the third magnetic layer. The third magnetic layer is nonuniformly thick such that a thickness of the third pole is less than a thickness of the third magnetic layer at locations in registry with the inductive coil. The magnetic write structure is conveniently fabricated by depositing the magnetic layers and the inductive coil, masking the third magnetic layer other than the third pole, and removing a portion of the thickness of the third pole.

Abstract: An apparatus for reader characterization is described. The apparatus includes a rotator for rotating a media. The media can contain a signal having a value for a function of a read/write head being assessed. The rotator is operable in conjunction with said apparatus. The apparatus also includes a proximator for proximalizing the media to the read/write head. The proximator is operable in conjunction with said apparatus. The apparatus further includes a writer operable in conjunction with said assembly. The writer writes the signal upon the media. The signal emits the value of the function. The signal is detectable by a reader of the read/write head. The apparatus additionally includes an interface operable in the apparatus for providing removable orientation of the read/write head in an assessing position. The assessing position enables a reader of the read/write head to detect the signal upon rotation of the signal through the assessing position.

Abstract: A hard disk drive (HDD) detects and measures external stray magnetic fields with existing HDD components. After detecting a strong external magnetic field, read and write operations of the HDD are suspended, and/or other proper corrective actions are taken to minimize loss of data. To measure the stray magnetic field, the magnetic head reader is used as a field sensor. The resistance of the reader changes in the presence of the field, such as with the preamp in the HDD. The resistance also changes with temperature. If the temperature inside the HDD is measured, the resistance change due to temperature is normalized. Even without being able to measure the HDD temperature, the stray magnetic field can be measured with a top head and a bottom head in the HDD. The temperature sensitivity of the reader is thereby cancelled out.

Abstract: One embodiment of the invention provides a system that characterizes cells within an integrated circuit. During operation, the system obtains a number of input noise signals to be applied to the cell. The system then simulates responses of the cell to each of the input noise signals, and stores a representation of the responses. This allows a subsequent analysis operation to access the stored representation to determine a response of the cell instead of having to perform a time-consuming simulation operation.

Abstract: A method and apparatus for providing a write head with an improved pole tip to improve overwrite and/or adjacent track interference. A cross pole tip writer is provided with a shape that is designed to reduce the saturation on the pole tip and aid in the concentration of flux to the down track.

Abstract: A magnetic head includes a magnetic write structure having a first magnetic layer having a first pole, a second magnetic layer having a second pole spaced apart from the first pole, and a third magnetic layer having a third pole contacting the second pole. The third pole has a third-pole width greater than a second-pole width. An inductive coil positioned adjacent to the third magnetic layer controllably magnetizes the third magnetic layer. The third magnetic layer is nonuniformly thick such that a thickness of the third pole is less than a thickness of the third magnetic layer at locations in registry with the inductive coil. The magnetic write structure is conveniently fabricated by depositing the magnetic layers and the inductive coil, masking the third magnetic layer other than the third pole, and removing a portion of the thickness of the third pole.

Abstract: One embodiment of the invention provides a system that analyzes the propagation of noise through an integrated circuit. During operation, the system obtains an input noise signal to be applied to a cell within the integrated circuit. The system then looks up parameters specifying how noise affects the cell, and then uses the parameters to determine how the input noise signal affects the cell. This can involve determining if the input noise signal will cause the cell to fail and/or determining a propagated noise signal that emanates from the cell.

Abstract: One embodiment of the invention provides a system that characterizes cells within an integrated circuit. During operation, the system obtains a number of input noise signals to be applied to the cell. The system then simulates responses of the cell to each of the input noise signals, and stores a representation of the responses. This allows a subsequent analysis operation to access the stored representation to determine a response of the cell instead of having to perform a time-consuming simulation operation.