Abstract: A method and apparatus for determining embedded runout correction values uses a closed-loop system (with feedback) in a disk drive. Optionally, the embedded runout correction values may be determined after the disk drive has been manufactured and placed in the field. In addition, the embedded runout correction values may be updated after the disk drive has been manufactured and placed in the field.

Abstract: A method for detecting a change in fly-height comprises measuring motor currents at various radii at a regular interval to determine the head drag. If any of the head drags at the various radii are greater than a threshold value, it is determined that a decrease in fly-height has occurred. If the disk drive has a head cleaner, a head cleaning is initiated to correct the fly-height change. If no head cleaning is necessary, a general error signal may be generated to indicate potential drive failure.

Abstract: A method for secondary-actuator failure-detection and recovery in a dual-stage actuator disk drive includes running a calibration test by the servo control processor and measuring the position of the secondary actuator relative to its neutral position in response to the calibration test. The secondary-actuator failure detection and calibration test can be performed on a regular schedule or at selected times, such as at disk drive start-up. With the primary actuator maintaining the read/write head on a data track in track-following mode, the servo control processor generates a test signal to the secondary actuator and receives a relative-position signal (RPS) from the relative-position sensor in response to the test signal. The test comprises two measurements: a measurement of the secondary actuator static characteristics, and a measurement of the secondary actuator dynamic characteristics.

Abstract: A hard disk drive contains magnetic disks which are accessed by a series of pivotable arms. Each arm has a pair of flexible, cantilevered suspensions and a head gimbal assembly with a magnetic read/write head secured to each suspension. A tab extends from and forms part of the end of each head gimbal assembly. The hard disk drive also has a stationary cam member located near the outer edges of the disks. The cam member has a series of rigid cantilevered fingers with contoured surfaces. Each surface has three spaced-apart detents with a recess located between each adjacent pair of detents. The second recess on each surface has a lubricant-filled reservoir. For the majority of its operation, the drive pivots the arms between an operational range adjacent to the disks, and a park position in the first recess when the drive is not in use. The tabs slide along the support surfaces of the fingers when the arms move to the retracted position.

Abstract: A disc drive servo system for controlling the drive of a disc carrying a binary digital signal wherein the digital signal includes (i) an information signal portion in which the position of an inversion of the digital signal is determined in accordance with an analog information signal and (ii) synchronizing signal portions which include two successive maximum periods of the inversion. The system comprises a timer means for initialing a timing operation upon receipt of an inversion signal and for producing an output signal when no inversion occurs during a time period which is twice as long as the maximum period of the inversion, thereby reproducing a synchronizing signal and ensuring precise control of the disc drive speed even during periods in which the production of a clock signal is not possible.

Abstract: The head base drive mechanism for cassette tape players. The head base which is normally urged toward the stop position is advanced to the play-back position using the rotation of the capstan. A pinion integrally provided on the flywheel of the capstan is engaged or disengaged with a sector gear. The sector gear is blocked from rotation after it goes out of said engagement and before it comes into engagement with the pinion. Since the sector gear is urged in a predetermined direction by way of a cam attached thereto, the release of said blocking causes the sector gear to rotate very quickly while the pinion is in facing relation to the untoothed position of the sector gear. Meantime, the cam actuates the head base to advance it to the play-back position through gear transmission whereas it restores the head base to the stop position quickly with the force by which the sector gear is urged.