Patent ID: 7646682

Claim:
A control apparatus for stabilizing a servo system in an optical electronic device, the optical electronic device including a focusing controller for outputting a focus control signal and an optical pick-up head for accessing an optical disk, the control apparatus comprising: a coupler that is configured to (a) receive a focus error signal outputted by the optical pick-up head, (b) receive a digital offset signal that is a direct current (DC) signal having a digital value encoded thereon, and (c) couple the focus error signal with the digital offset signal to generate a coupled signal according to the focus error signal and the digital value encoded on the digital offset signal; and a focus compensator that is configured to receive the coupled signal and to output the focus control signal to control a focus point of the optical pick-up head; wherein the optical electronic device reads data during a first operating state and seeks a track during a second operating state, wherein during the first operating state a first digital value is encoded on the digital offset signal such that the focusing of the optical pick-up head is regulated onto a first focus point, and wherein during the second operating state, the digital value encoded on the digital offset signal is different than the first digital value such that the focusing of the optical pick-up head is regulated away from the first focus point by a distance that is based on a value of the focus error signal.