US Patent 7606119 Objective lens actuator

In one preferred embodiment, an objective lens actuator includes a base, a suspension apparatus mounted on the base, a holder suspended by the suspension apparatus for holding an objective lens, a voice coil motor (VCM) for driving the holder to vibrate, and a cover. The VCM includes a first yoke, a second yoke and a pair of magnets fixed on the first yoke and the second yoke respectively. The first yoke and the second yoke respectively include a first part and a second part. The cover is made of a material having a magnetic conductivity. The cover connects the first part and the second part of each of the first yoke and the second yoke.