International Business Machines Corporation

Akimitsu Sasaki

Nhan Xuan Bui

John Alexander Koski

Kazuhiro Tsuruta

Keisuke Tanaka

Tomoaki Kimura

A method and apparatus for compensating for media shift due to spiral groove roller tape guide is disclosed. The lateral tape shift is measured. Then the control of the coarse actuator is adjusted for the lateral tape shift so that the movement of the coarse actuator follows the tape shift.

Method and apparatus for compensating for media shift due to tape guide

A method and apparatus for providing linear position (LPOS) estimations. If valid LPOS data may be detected from the tape, then a first method for LPOS estimation is performed using the Hall effect sensors. If valid LPOS data may not be detected from the tape, then an error recovery procedure (ERP) is invoked so that a second method for LPOS estimation is used to provide accurate LPOS information which is synchronized to a validly detected LPOS from tape within about 1 meter prior to the desired data record.

Method and apparatus for providing linear position (LPOS) estimations

Method and apparatus for performing position error signal conditioning of LTO media servo format written-in velocity variation

A method and position control for a servo system for positioning a head laterally with respect to defined servo tracks. The servo system comprises a servo sensor and detector for sensing lateral position of the head and a compound actuator having a fine actuator portion and a coarse actuator portion. The position control provides position indications for the coarse actuator portion, which may comprise a table relating predetermined nominal lateral position indications to the defined servo tracks. The position control positions the coarse actuator portion at an estimated position with respect to the defined servo tracks, and responds to the servo sensor to determine which servo track is closest to the estimated position. The position control sets the coarse actuator portion position indication to the predetermined nominal lateral position indication of the closest defined servo track, e.g., by looking it up in the table. This thereby corrects the indication of the position of the coarse actuator portion.

Position identification for a coarse actuator portion of a compound actuator

In a tape drive system performing read/write operations on a tape by inserting a tape cartridge into a tape drive, the tape cartridge having a tape on which servo and data tracks are arranged longitudinally and a predetermined servo pattern is recorded on each of the servo tracks, a method and system for re-setting coefficients of a low-pass filter for servo control of the tape drive, each time the tape cartridge is inserted into the tape drive so that a servo system of the tape drive is stabilized. More specifically, the servo pattern is read from the tape in the cartridge inserted into the tape drive, frequency analysis for the read servo pattern is performed, a singularity that exceeds a predetermined spectrum range is detected from frequency components obtained by the frequency analysis, and the coefficients of the low-pass filter are set so as to cancel a power spectrum of the singularity.

Tape drive and servo system stabilization method

Method and apparatus for detecting and computing tape reel radius using low-resolution angular position sensors

A servo system and method position a head laterally with respect to defined servo tracks, employing fine and coarse actuators. A servo control integrates the position error between the head and a desired position in accordance with a predetermined function, and operates the coarse actuator to translate the fine actuator and the head in accordance with the integrated position error. A position error signal loop is coupled to a servo sensor for determining position error for operating the fine actuator to translate the head in a manner to reduce the position error. The position error signal loop may have a compensator function with both integration and other functions. A coarse servo control comprises a connection coupled to the compensator function for providing an integration control representing the integration function of the position error signal loop; and a driver coupled to the connection, operating the coarse actuator to translate the fine actuator and the head in accordance with the integration signal.

Servo control of a coarse actuator

A servo system and method position a head laterally with respect to magnetic tape longitudinal defined servo bands arranged in a longitudinally shifted pattern for identification, and separated by data tracks. A servo controller responds to a loss of lateral position, sensing an estimated longitudinal position of the magnetic tape. If the estimated longitudinal position is within a predetermined distance of an end of the tape, the servo controller operates a drive to continuously move the tape away from the sensed end. The servo controller senses a home lateral position sensor to determine whether a compound actuator is within a predetermined distance of the edge of the magnetic tape. If so, it operates the coarse actuator portion of the compound actuator to move laterally away from the edge of the magnetic tape; else, to move toward the edge. The servo controller senses a dual servo sensor to detect any two of the defined servo bands; and, upon sensing any two of the defined servo bands, detects the longitudinal shift to identify which ones of the two defined servo bands have been detected.

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Yokohama, Japan

Akimitsu Sasaki