Abstract: A novel wavelength routing apparatus is disclosed, which uses a diffraction grating to separate a multi-wavelength optical signal from an input port into multiple spectral channels; a channel-interleaving assembly (e.g., an array of prisms) to interleave the spectral channels into two channel groups; and an “augmented relay system” to relay the interleaved channel groups onto two separate arrays of channel micromirrors, respectively. The channel micromirrors are individually controllable and pivotable to reflect the spectral channels into multiple output ports. As such, the inventive wavelength routing apparatus is capable of routing the spectral channels on a channel-by-channel basis and coupling any spectral channel into any one of the output ports.

Abstract: A transducer position sensing system in a disc drive to take frequent data measurements from micro-servo sectors on the disc and to interpret the information to predict recording failures. The disc drive is formatted with many small or micro-servo sectors containing, among other things, a servo address mark, encoded disc location information, and radial track position information. The sensing system frequently retrieves this information through the transducer, compares the measurements to expected values, and given unexpected measurements predicts errors. The time elapsed between the passing of servo address marks can be used to predict adjacent sector overwrites. The radial track position information can be used to predict off-track write errors. The radial track position signal amplitude can be used to predict the transducer moving too far from the disc, resulting in skip write errors.

Abstract: A propagating method is provided in which timing and servo sector information is propagated throughout a data storage media that initially contains only a guide pattern. The method uses an offset between the write element and the read element in a read/write head to position and propagate the timing information. In addition, a method for circumferentially aligning timing and servo sector information is disclosed that utilizes a time delay to position the propagated timing and servo sector information. Another method for attenuating timing errors during timing and servo sector propagation to a data storage media is disclosed. Timing errors are attenuated through the use of phase locked loop circuit and measurement of the phase error detected between different tracks on the data storage media. Apparatuses implementing the methods including a storage device readable by a computer system that implements the methods are provided.

Abstract: A method and apparatus for reading and writing data from and to a data storage disc in a data storage device. The data storage disc includes a first disc surface and second disc surface for storing data. The data storage device includes an actuator assembly configured to selectively position a first transducer over the first disc surface and a second transducer over the second disc surface, wherein the first transducer is substantially identical to the second transducer. Furthermore, each transducer includes a read element and a write element, wherein the read element is offset from the write element by at least the width of one servo track.

Abstract: A perpendicular magnetic recording media with a patterned soft magnetic underlayer is disclosed. The recording media may be a disk including a substrate, a patterned underlayer, and a magnetically hard recording layer. The underlayer may be provided in the form of concentric bands having widths less than the track widths of the recording layer. The patterned underlayer reduces or eliminates adjacent track interference.

Abstract: This invention provides a novel wavelength-separating-routing (WSR) apparatus that uses a diffraction grating to separate a multi-wavelength optical signal by wavelength into multiple spectral channels, which are then focused onto an array of corresponding channel micromirrors. The channel micromirrors are individually controllable and continuously pivotable to reflect the spectral channels into multiple output ports. As such, the inventive WSR apparatus is capable of routing the spectral channels on a channel-by-channel basis and coupling any spectral channel into any one of the output ports. The WSR apparatus of the present invention may be further equipped with servo-control and spectral power-management capabilities, thereby maintaining the coupling efficiencies of the spectral channels into the output ports at desired values.

Abstract: A novel wavelength routing apparatus is disclosed, which uses a diffraction grating to separate a multi-wavelength optical signal from an input port into multiple spectral channels; a channel-interleaving assembly (e.g., an array of prisms) to interleave the spectral channels into two channel groups; and an “augmented relay system” to relay the interleaved channel groups onto two separate arrays of channel micromirrors, respectively. The channel micromirrors are individually controllable and pivotable to reflect the spectral channels into multiple output ports. As such, the inventive wavelength routing apparatus is capable of routing the spectral channels on a channel-by-channel basis and coupling any spectral channel into any one of the output ports.

Abstract: A propagating method is provided in which timing and servo sector information is propagated throughout a data storage media that initially contains only a guide pattern. The method uses an offset between the write element and the read element in a read/write head to position and propagate the timing information. In addition, a method for circumferentially aligning timing and servo sector information is disclosed that utilizes a time delay to position the propagated timing and servo sector information. Another method for attenuating timing errors during timing and servo sector propagation to a data storage media is disclosed. Timing errors are attenuated through the use of phase locked loop circuit and measurement of the phase error detected between different tracks on the data storage media. Apparatuses implementing the methods including a storage device readable by a computer system that implements the methods are provided.

Abstract: A magneto-resistive (M-R) head has a read element with a servo sensing width as wide as a data track width and a data sensing width of less than one data track width. The two read sensing widths are achieved by using a single read element having a center electrical contact from the M-R read element that effectively reduces the sensing width of the read element. In a first embodiment, the servo sensing width comprises a first portion of the read element and the data sensing width comprises a second, smaller portion of the read element. In a second embodiment, the servo sensing width comprises the entire read element width and the data sensing width comprises a portion thereof. In yet another embodiment, abutting read elements are constructed to enable separate optimization of each sensing width. The wide servo sensing width permits use of a wide servo pattern having servo bursts as wide as a data track width.

Abstract: This invention provides a novel wavelength-separating-routing (WSR) apparatus that uses a diffraction grating to separate a multi-wavelength optical signal by wavelength into multiple spectral channels, which are then focused onto an array of corresponding channel micromirrors. The channel micromirrors are individually controllable and continuously pivotable to reflect the spectral channels into multiple output ports. As such, the inventive WSR apparatus is capable of routing the spectral channels on a channel-by-channel basis and coupling any spectral channel into any one of the output ports. The WSR apparatus of the present invention may be further equipped with servo-control and spectral power-management capabilities, thereby maintaining the coupling efficiencies of the spectral channels into the output ports at desired values.

Abstract: A disc drive has a disc for storing information with the disc having a radius and an outer circumference. The actuator assembly is rotatable about a rotational axis with the rotational axis of the actuator assembly being positioned within the outer circumference of the disc. The length of the actuator assembly between the magnetic head and the rotational axis being less than or equal to the radius of the disc. A method for securing an actuator assembly within a disc drive is also provided.

Abstract: A perpendicular magnetic recording media with a patterned soft magnetic underlayer is disclosed. The recording media may be a disk including a substrate, a patterned underlayer, and a magnetically hard recording layer. The underlayer may be provided in the form of concentric bands having widths less than the track widths of the recording layer. The patterned underlayer reduces or eliminates adjacent track interference.

Abstract: A transducer position sensing system in a disc drive to take frequent data measurements from micro-servo sectors on the disc and to interpret the information to predict recording failures. The disc drive is formatted with many small or micro-servo sectors containing, among other things, a servo address mark, encoded disc location information, and radial track position information. The sensing system frequently retrieves this information through the transducer, compares the measurements to expected values, and given unexpected measurements predicts errors. The time elapsed between the passing of servo address marks can be used to predict adjacent sector overwrites. The radial track position information can be used to predict off-track write errors. The radial track position signal amplitude can be used to predict the transducer moving too far from the disc, resulting in skip write errors.

Abstract: A method and apparatus for reading and writing data from and to a data storage disc in a data storage device. The data storage disc includes a first disc surface and second disc surface for storing data. The data storage device includes an actuator assembly configured to selectively position a first transducer over the first disc surface and a second transducer over the second disc surface, wherein the first transducer is substantially identical to the second transducer. Furthermore, each transducer includes a read element and a write element, wherein the read element is offset from the write element by at least the width of one servo track.

Abstract: A method and apparatus for locating more accurately the beginning of data cells stored on a medium with embedded servo sectors and improving the efficiency with which data can be stored on a medium as a consequence of more accurately locating the beginning of data cells stored on the medium. A counter counts the number of cycles of a clock. Initially, the counter is reset to zero upon recognition of a valid servo identification pattern (SID). When a terminal count value representative of the elapse of time until the end of a servo sector is reached, the counter is loaded with a negative value and continues to count. Upon detecting the next SID, the value of the counter should be equal to zero if an estimated time between detection of the last SID and the current SID was equal to the actual time between detection of the two SIDs. If the value of the counter is positive, then the current SID arrived under the head later than expected.

Abstract: A servo pattern for use on a data storage surface that includes at least one track to minimize position error during positioning of a transducer over the data storage surface. The servo pattern includes a plurality of servo burst fields of constant amplitude for defining a centerline of the track and for determining the position of the transducer. According to the present invention, at least one servo burst field comprises N segments, where N.gtoreq.2, and each of the N segments is written with constant amplitude. The amplitude of the at least one servo burst field is then determined as a function of the amplitudes of the N segments.

Abstract: In a subsystem for accessing addressable ECC-coded sectors of magnetic disk tracks subject to sector level redundancy group organization, a method is described for managing write updates to said sectors by maintaining a current set of all redundant sectors in a subsystem NVS buffer external to the DASD such that only a read access of the DASD sector to be modified need be made. This derives from the availability of the new record data and the old redundant sector information at the subsystem. The redundant sector is modified by logically combining the old redundant sector and the new and old data sectors and is saved to the buffer and asynchronously copied to DASD subsequently.

Abstract: A method and apparatus for generating very small split tables from an even smaller amount of information preferably stored on a medium in a system track. The present invention takes advantage of the fact that the pattern of split data cells is periodic. Each split table can be generated upon initial application of power from a relatively few parameters stored in the system track. A method is provided by the present invention for generating each split table based upon the zone number, the number of track wedges within the period of the repeat pattern, the rate at which data is to be written in the zone and two additional parameters. In addition, the present invention is a method and apparatus for increasing the efficiency of the medium by adjusting the size of each zone to minimize the number of split data cells stored on the medium. In accordance with the present invention, the size of each zone is selected based upon the length of the repeat pattern.

Abstract: In accordance with the present invention a storage device servo control system that positions a head relative to multiple tracks of a storage medium includes a servo signal filter that receives a readback signal from the head and produces filtered servo signal data samples, a servo demodulator that receives the filtered readback servo signal from the servo signal filter and produces a position error signal that indicates the head position relative to a track using a demodulation scheme selected in accordance with a track width profile of the storage device, and includes a servo controller that determines the demodulation scheme to be used by the servo demodulator and that processes the position error signal to maintain the head centered relative to the track.

Abstract: Servo pattern bursts are recorded with two frequencies that are detected using heterodyne detection with oscillators at the same frequency as the respective recorded frequencies. The two frequencies are selected to be orthogonal so the sensed servo pattern of one frequency is zero when detected with the detecting circuitry of the other frequency. The servo pattern bursts of the two frequencies are placed close together on the disk so they are sensed simultaneously so that, with orthogonality processing, a PES signal from a three phase pattern is sufficient to provide a robust linear signal, thereby eliminating one of the bursts from a quadrature pattern and reducing the disk surface area needed in each track for the servo pattern by 25% or more.