Mask Alignment for a Capacitative-Servo Disk
Original Publication Date: 1988-Sep-01
Included in the Prior Art Database: 2005-Feb-15
Techniques for centering 14-inch capacitative-servo disks to a precision of one micron for increasing track density on the disk involve optical or capacitive measurements. When a disk is asymmetrically mounted on a rotating jig whose axis of rotation is fixed in space, the center of the disk will follow a circular path, denoted as P in Fig. 1. In the figure wr is the amount of misalignment, that is, the distance between the center of the disk C and the axis of rotation A. When the jig rotates with a constant angular velocity wo, defining a time t=0 also defines a phase angle do with respect to xy-Cartesian coordinate system fixed in space and in time.