Patent ID: 7663829

Claim:
A method for testing a performance of a head gimbal assembly including a magnetic head and a micro-actuator for precisely positioning the magnetic head with respect to a magnetic medium, the method comprising steps of: (1) writing an initial track of information onto the magnetic medium, reading out the initial track of information, measuring an initial track average amplitude profile of the read-out initial track information, and calculating a track center value OFFSET 1 according to the initial track average amplitude profile; (2) judging whether an operating direct current voltage to be applied to the micro-actuator is higher than a threshold value or not, if NO, performing steps (3)-(6), if YES, performing steps (7)-(9); (3) moving the magnetic head toward an off-track direction by a predetermined distance D; (4) applying the operating direct current voltage to the micro-actuator to drive the micro-actuator displacement in a positive direction and simultaneously writing a first track of information onto the magnetic medium, reading out the first track of information, measuring a first track average amplitude profile of the read-out first track of information, and calculating a track center value OFFSET 2 according to the first track average amplitude profile; (5) applying the operating direct current voltage to the micro-actuator to drive the micro-actuator displacement in a negative direction and simultaneously writing a second track of information onto the magnetic medium, reading out the second track of information, measuring a second track average amplitude profile of the read-out second track of information, and calculating a track center value OFFSET 3 according to the second track average amplitude profile; (6) calculating the displacement of the micro-actuator according to a formula, the formula being ((OFFSET 2 −OFFSET 1 −D)+(D−(OFFSET 3 −OFFSET 1 )))/2; (7) applying the operating direct current voltage to the micro-actuator to drive the micro-actuator displacement in a positive direction and simultaneously writing a first track of information onto the magnetic medium, reading out the first track of information, measuring a first track average amplitude profile of the read-out first track of information, and calculating a track center value OFFSET 2 ′ according to the first track average amplitude profile; (8) applying the operating direct current voltage to the micro-actuator to drive the micro-actuator displacement in a negative direction and simultaneously writing a second track of information onto the magnetic medium, reading out the second track of information, measuring a second track average amplitude profile of the read-out second track of information, and calculating a track center value OFFSET 3 ′ according to the second track average amplitude profile; and (9) calculating the displacement of the micro-actuator according to a formula, the formula being (OFFSET 2 ′+OFFSET 3 ′)/2.