Abstract: An apparatus for compensating for radial and vertical runout of an optical disc using an actuator having a lens for focus of a laser beam and wherein the focus and tracking currents control the position of the lens in the vertical and radial directions is disclosed. The apparatus focuses the actuator lens along at least one revolution of a track on an optical disc and producing lens position signals. Structures provided which responds to the lens position signals to produce the frequency content of surface height and track deviations of the optical disc using a frequency transform technique. The surface height and track deviations frequency content are stored and a signal representing the focusing and tracking actuator currents and in response to the focusing and tracking actuator current signals and the stored surface height and track deviation frequencies the lens position is controlled thereby reducing focusing and tracking errors.

Abstract: A method for deriving a track offset signal to be applied to a tracking error signal particularly adapted for use with a disc drive having a servomechanism and actuator for positioning a read or write spot on a track of a disc in response to the tracking error signal is disclosed. The method includes determining a signal representation of the focus height as a function of disc radius, and differentiating the focus height signal to derive a cross-track tilt signal, applying the cross-track tilt signal to a transform which produces a track offset signal.

Abstract: A method for detecting and processing synchronization marks extracted from a prerecorded wobbled groove formed in a compact disk in order to produce pseudo-sync signals using a high frequency phase locked loop servoing to the disk speed to generate the signals.

Abstract: The present method operates upon an optical disk type servo-system of the type having an optical tracking servo for maintaining a lens centered over a track on a disk and a tracking position servo for moving an optical head's lens to a desired position. Included within such a system is an eccentricity sub-system for providing a compensating sine wave signal for reducing errors in tracking due to disk decentering. The present method automatically adjusts the gain in one of the servos to match the gain appearing in the other servo so as to improve the smoothness of control when switching between the servos.

Abstract: Track jumping in the present system is accomplished by using a two step track jump method which accelerates the tracking actuator toward the desired track at maximum acceleration and then decelerates the tracking actuator at a maximum deceleration so that the desired track is reached in a minimum amount of time without the actuator ringing. A matrix containing the times for each jump pulse from track X to track Y is recorded. The matrix table is updated after each jump to compensate for variance factors. The table is stored in memory which allows the system to become more accurate with each jump. If the actuator falls short of the desired position, the jump pulse next applied is lengthened slightly. If the jump pulse causes the actuator to overshoot, the desired position the jump pulse is shortened for the next jump.

Abstract: The present invention automatically performs a series of measurements on an optical media based on writing a power ramp signal of known power levels (amplitudes) on a target sector of the optical media. The amplitudes of the written power levels are measured. A comparison of the measured amplitude of each level of the recorded power ramp signal against reference amplitudes is made to establish a matching factor. The power level having the closest matching factor is selected as the power level to be used for the best recording of data onto the optical media. The procedure may be iterated a number of times to form an average that can then be used as the write power level. The present method also provides a pre-emphasis calibration by writing a pre-emphasis ramp in a target sector which is compared against a desired duty cycle to select the pre-emphasis which yields the desired duty cycle.