Patent ID: 6349464
Filing Date: 2002-02-26
Classification: G11B,Y10T

Abstract:
A method of making a balance-compensated (BC) rotary actuator for use in a rotatable BC head stack assembly (HSA) portion in a disk drive based upon track-follow performance of a rotatable test HSA portion, the test HSA portion including a test rotary actuator having a test actuator weight distribution specification, the test rotary actuator having an actuator body portion, a test pivot axis extending through the actuator body portion and a head connected to the actuator body portion, the test rotary actuator being controlled to rotate about the test pivot axis for positioning the head over a selected disk track, the method comprising the steps of:a) vibrating the disk drive at a vibration frequency in order to vibrate the test HSA portion; b) reading position error information using the head while performing a track-follow operation during the vibrating of the test HSA portion; c) determining head off-track error due to the vibration of the disk drive based upon the read position error information representative of positioning of the head relative to the selected disk track; d) deriving a resultant torque vector based upon the determined head off-track error, the resultant installed torque vector having a magnitude equal to a mass of the test HSA portion times a distance between the test pivot axis and a test installed HSA portion center-of-gravity, the test installed HSA portion center-of-gravity taking into consideration forces acting upon the test rotary actuator due to installation with the test HSA portion, the resultant torque vector having a direction extending perpendicular from the test pivot axis towards the test installed HSA portion center-of-gravity; e) deriving a balancing torque vector having a magnitude equal to and a direction opposite of the resultant torque vector; f) producing a BC actuator weight distribution specification based upon the test actuator weight distribution specification and the balancing torque vector; and g) using the BC actuator weight distribution specification to manufacture the BC rotary actuator having a BC pivot axis, the BC HSA portion having a BC installed HSA center-of-gravity at the BC pivot axis for mitigating external acceleration applied to the BC rotary actuator about the BC pivot axis due to external linear acceleration experienced by the disk drive during a track-follow operation.