Gear transmission system for an optical disk drive

A disk drive includes a gear transmission system disposed within a casing. The gear transmission system includes first and second gears, a driven plate having a first serrated portion meshed with the first gear, a second serrated portion facing a third gear, and first and second guiding slots. A lifting frame has two couplers slidably engaging with the slots in the driven plate. Rotation of the third gear alternately in opposite directions results in movement of the driven plate in right and left sides of the casing, which, in turn, results in lifting of the frame to an upper reading position, in which, a resilient pushing arm of the lifting frame abuts against the driven plate to provide resilience between the second serrated portion and the third gear.