Patent ID: 6989949

Claim:
A method for testing a performance of a head gimbal assembly including a magnetic head slider with at least one thin-film magnetic head element, a support and an actuator for displacing said magnetic head slider with respect to said support so as to precisely position said at least one thin-film magnetic head element, said method comprising steps of: writing information from said at least one thin-film magnetic head element onto a magnetic disk while driving said actuator for displacement by applying an alternating drive signal to said actuator to write a track of information having an alternating center line shape; reading out the information of at least one rotation of said magnetic disk by said at least one thin-film magnetic head element without driving said actuator for displacement; storing the information read-out from said magnetic disk as a read-out information along a disk-rotating direction; moving said head gimbal assembly toward an off-track direction by a predetermined distance; repeatedly executing said reading, storing and moving steps to obtain two-dimensional read-out information along the disk-rotating direction and the off-track direction; and determining, from said two-dimensional read-out information, an off-track position where the read-out information becomes maximum at each position along the disk-rotating direction, the determined off-track positions being recognized as displaced positions of said actuator in response to the applied alternating drive signal.