Optical Disk Drive Lens Centering
Original Publication Date: 1987-Jul-01
Included in the Prior Art Database: 2005-Feb-01
In an optical disk drive, a lens carriage positions the lens such that the lens is ideally always exactly perpendicular to the disk's data track being accessed. However, if the carriage positioning system is limited to discrete positions (for example, the carriage is driven by a stepper motor), and the disk's data track is eccentric, the best carriage position that can be achieved is a position such that the lens' radial excursions from this ideal perpendicular state are minimized. Since a centered state is frequently disrupted (on lens movement seeks across the disk), the method to reachieve the centered state must be fast in order to minimize the impact on the rated access time of the disk drive. Immediately after acquiring a state where the head is tracking, control logic begins sampling the lens position.