Head-disk interface tester with optically servo controlled rotary voice coil motor actuator

摘要

A head-disk interface tester for magnetic recording disk drives uses a rotary voice coil motor (VCM) actuator and a rotating laser beam that rotates with the actuator to accurately move the head to the desired position and with the desired velocity. A diode laser is located on the rotating actuator and directs a laser beam through the pivot axis of the actuator. The laser beam is received by a linear position detector. The detector provides position data which is used by control circuitry to move the actuator to the position determined by the user or according to a velocity determined by the user. The rotary VCM actuator is mounted on an adjustable stage that allows the height of the actuator to be varied, as well as the distance between the actuator pivot axis and the spindle motor rotation axis to be varied. The VCM actuator is also removable from its mount so that it can be repositioned to locate the head on either side of the disk center to enable the tester to simulate the head-disk interface of both top and bottom disk surfaces. The tester includes an adjustable load/unload ramp, which together with the preselected velocity mode of operation, allows accurate simulation of a wide range of disk drives that load and unload their heads on ramps with a specific velocity.