Abstract: In accordance with the present invention, a method of operating a magnetic tape drive, a magnetic tape drive and a servo control system are provided for obtaining and maintaining velocity control in a magnetic tape drive. In one embodiment, a method is provided for operating a magnetic tape drive. The tape drive includes a plurality of DC motors, and each DC motor has a plurality of Hall sensors. The DC motors are under the control of a servo system which is configured to read location information from the magnetic tape, and compute a primary tape velocity from the location information, and sense a secondary and tertiary velocity signal and compute a tape velocity based on one of the sensed secondary velocity signal and tertiary velocity. The method includes detecting if the primary velocity location information is available. In response to detecting that the primary velocity location information is available the primary velocity is employed to control the servo system.

Abstract: A method to adjust the positions of a write element and read element disposed on a read/write head comprising a first assembly independently moveable along a first axis and comprising a first servo element, a second servo element, and the write element disposed between the first servo element and the second servo element and a second assembly independently moveable along the first axis and comprising a third servo element, a fourth servo element, and the read element disposed between the third servo element and the fourth servo element. The method moves a sequential information storage medium adjacent to the read/write head along a second axis, wherein the second axis is substantially orthogonal to the first axis, and determines a dynamic skew for the sequential information storage medium with respect to the read/write head using the first servo element and the second servo element. The method then positions the first assembly with respect to the second assembly to correct for that dynamic skew angle.

Abstract: A servo detection system for detecting servo tracks of a longitudinal tape. In a read/write head, two servo read heads are spaced laterally on a first head module, and a servo read head is on a second head module spaced longitudinally from the first module. A method comprises initially sensing a tape servo track with one servo read head of the first module and the servo read head of the second module to determine skew misalignment of the servo track. A zero reference value is stored representing the determined skew misalignment. The detection system switches from the one servo read head of each module, to the two servo read heads of the first module, and employs the stored value to position the read/write head in the zero skew position. The two servo read heads are then employed to read two servo tracks to identify the data band and to control skew.

Abstract: A method and apparatus is presented to determine a lateral position of a read/write head relative to a sequential information storage medium having a servo signal encoded therein and moving adjacent to the read/write head, where the servo signal comprises a plurality of pulses. The method includes detecting the servo signal using the read/write head and calculating a timing interval between each of the pulses using a clock rate of a clock signal. The clock rate is then adjusted based upon the velocity of the sequential information storage medium.

Abstract: Methods, servo systems, and data storage drives follow the lateral shift excursions of longitudinal tape, for example, from flangeless tape guides. A servo sensor is configured to sense lateral position of a tape head with respect to longitudinal servo tracks of the tape, a fine actuator is configured to translate the head laterally, and a coarse actuator is configured to translate the fine actuator laterally. Position error is determined between the head and a desired position related to the servo track, and the fine actuator operated to translate the head laterally to reduce the position error. In the embodiment, lateral shift excursion is sensed from the position error, and the coarse actuator is positioned substantially at a midpoint of the lateral shift excursion. Thus, the fine actuator follows the lateral shift excursions, while the coarse actuator remains at the midpoint.

Abstract: An apparatus, system, and method are disclosed for dynamic tape stick and tape break detection. A first counter increments a first count and resets a second count in response to a sensor pulse from a first sensor of a first tape servo. A second counter increments the second count and resets the first count in response to a sensor pulse from a second sensor of a second tape servo. A detection module detects either the first count or the second count exceeding an error threshold.

Abstract: An apparatus for controlling an electric motor is provided. A plurality of switches is provided for controlling a direction of current through motor coils of the electric motor. A brushless motor control circuit is connected to each of the plurality of switches. Responsive to a request to adjust one of an angular velocity and an angular acceleration of the electric motor, the plurality of switches are activated to place the motor coils in a predetermined configuration to maximize torque or reduce a total back electromotive force (BEMF) from the motor coils.

Abstract: A method, a servo system and a tape drive are provided to acquire lock on a servo signal. The servo signals of at least one servo element are monitored to detect a valid servo signal. If a valid servo signal is not detected than the fine actuator is moved in a first direction until either a valid servo signal is detected or the fine actuator travel limit is reached. When a valid servo signal is detected, the fine actuator is set to a neutral position and the coarse actuator is moved in the first direction. When the fine actuator travel limit is reached the fine actuator is moved to the first position and the coarse actuator is moved in a second direction, opposite of the first direction.

Abstract: A method is presented to rotate a read/write head rotatable along a first axis and comprising a first assembly having a first servo element and a second servo element. The method moves a sequential information storage medium adjacent to the read/write head along a second axis, wherein the second axis is substantially orthogonal to the first axis, and determines the rotation angle for the read/write head with respect to the sequential information storage medium using the first servo element and the second servo element. The method then positions the read/write head with respect to the second axis based upon the rotation angle.

Abstract: A method is presented for setting a wrap angle of a read/write head having a servo element and multiple read elements, where the servo element and the read elements can detect a servo signal. The method includes moving a sequential information storage medium having a longitudinal axis and a servo band encoded therein adjacent to the read/write head. The longitudinal axis and a flat upper surface of the read write head define the wrap angle. The method further includes detecting the servo signal using one of the read elements. If the read element is unable to detect the servo signal, then the remaining read elements are sensed to detect the servo signal.

Abstract: A method to decode linear position (“LPOS”) information encoded in a sequential information storage medium, by detecting each of one or a plurality of sequential first LPOS servo patterns encoded in a first servo band using a first servo sensor in communication with a first servo channel. While detecting that one or a plurality of first LPOS servo patterns, the method fails to detect (n) second LPOS servo patterns encoded in a second servo band. The method determines a value for (n), and then syncs the first servo channel with the second servo channel using that value of (n).

Abstract: A method to adjust the orientation of a read head comprising a first read element and a second read element, wherein the first read element and the second read element are separated by a distance, wherein the method moves a sequential information storage medium adjacent to the read head, determines a skew angle for the sequential information storage medium with respect to the read head using the first read element and the second read element, and encodes that skew angle in a computer readable medium.

Abstract: Methods, servo systems, and data storage drives follow the lateral shift excursions of longitudinal tape, for example, from flangeless tape guides. A servo sensor is configured to sense lateral position of a tape head with respect to longitudinal servo tracks of the tape, a fine actuator is configured to translate the head laterally, and a coarse actuator is configured to translate the fine actuator laterally. Position error is determined between the head and a desired position related to the servo track, and the fine actuator operated to translate the head laterally to reduce the position error. In the embodiment, lateral shift excursion is sensed from the position error, and the coarse actuator is positioned substantially at a midpoint of the lateral shift excursion. Thus, the fine actuator follows the lateral shift excursions, while the coarse actuator remains at the midpoint.

Abstract: Methods, magnetic tape data storage drives, data storage systems, and magnetic tape data storage cartridges. A system having at least one magnetic tape data storage drive is configured to handle a magnetic tape cartridge comprising a magnetic tape data storage media and accompanying cartridge memory. The magnetic tape media comprises a plurality of longitudinal servo bands, the servo bands separated by data bands. Two servo bands, each at opposite sides of a data band are sensed. In response to at least one servo detection error signal of one of the two servo bands, an edge stress signal is set to the cartridge memory of the magnetic tape cartridge. Then, for example, after reloading the cartridge, the cartridge memory is inspected for a set edge stress signal; and, if the edge stress signal is set, only read operations are allowed with respect to the inspected magnetic tape data storage cartridge.

Abstract: A method and a system are provided for writing a plurality of servo bands on magnetic tape. The magnetic tape is moved longitudinally relative to at least one servo write head. The servo write head is positioned to write a plurality of parallel longitudinal servo bands. The plurality of servo bands comprise odd servo bands and even servo bands, and each of the odd servo bands lie between the each of the even servo bands. The at least one servo write head is operated to write the plurality of parallel longitudinal servo bands on the magnetic tape such that each of the plurality of servo bands comprise a plurality of frames, wherein each frame comprises a plurality of bursts of transition stripes, and each burst has a first transition stripe.

Abstract: A magnetic tape cartridge including magnetic tape with servo information is provided. The servo information comprises a plurality of parallel longitudinal servo bands that lie between a plurality of longitudinal data bands. The plurality of servo bands include odd servo bands and even servo bands, wherein each of the odd servo bands lie between each of the even servo bands. Each of the plurality servo bands include a plurality of frames, wherein each frame includes a plurality of bursts of transition stripes, and each burst having a first transition stripe. The first transition stripe of each burst of each the odd servo band is longitudinally shifted from the first transition stripe of each burst of each even servo band by a substantially equal distance, D, such that servo information of the odd servo bands is interleaved with the servo information from the even servo bands.

Abstract: A method and apparatus is presented to determine a lateral position of a read/write head relative to a sequential information storage medium having a servo signal encoded therein and moving adjacent to the read/write head, where the servo signal comprises a plurality of pulses. The method includes detecting the servo signal using the read/write head and calculating a timing interval between each of the pulses using a clock rate of a clock signal. The clock rate is then adjusted based upon the velocity of the sequential information storage medium.

Abstract: A method to position a head module, where the head module comprises at least one servo element and a plurality of data elements, where the servo element and each of the plurality of data elements can detect a servo signal, wherein the method includes moving a sequential information storage medium having a servo band encoded therein across the head module and detecting the servo band using the at least one servo element or any one of the plurality of data elements.

Abstract: A method is presented for setting a wrap angle of a read/write head having a servo element and multiple read elements, where the servo element and the read elements can detect a servo signal. The method includes moving a sequential information storage medium having a longitudinal axis and a servo band encoded therein adjacent to the read/write head. The longitudinal axis and a flat upper surface of the read write head define the wrap angle. The method further includes detecting the servo signal using one of the read elements. If the read element is unable to detect the servo signal, then the remaining read elements are sensed to detect the servo signal.

Abstract: A method is presented to rotate a read/write head rotatable along a first axis and comprising a first assembly having a first servo element and a second servo element. The method moves a sequential information storage medium adjacent to the read/write head along a second axis, wherein the second axis is substantially orthogonal to the first axis, and determines the rotation angle for the read/write head with respect to the sequential information storage medium using the first servo element and the second servo element. The method then positions the read/write head with respect to the second axis based upon the rotation angle.