Patent ID: 6898043

Claim:
A method of writing servo patterns on a disc in an external servo track writer (“STW”) including a spindle motor and an actuator assembly having an actuator arm and a dedicated servo writing head, the method comprising steps of: (a) loading the disc on a spindle shaft of the spindle motor; (b) enclosing the disc and the actuator arm within an internal enclosure; (c) closing an outer cover to form an enclosed environment that surrounds the internal enclosure; (d) activating the spindle motor and the actuator assembly to load the head on the disc; (e) filling the internal enclosure with a low-density gas to achieve a predetermined concentration and pressure of the low-density gas within the internal enclosure; (f) writing the servo patterns on the disc while the internal enclosure is filled with the low-density gas; (g) opening the internal enclosure once the servo patterns have been written to the disc; (h) purging the low-density gas from the enclosed environment of the external STW to recover the low-density gas while the outer cover remains closed; and (i) opening the outer cover to access the disc once a predetermined amount of the low-density gas has been recovered.