US Patent 7111311 Optical pickup device

A shock absorber includes a projection that projects toward an optical disk and projects out of a surface of an objective lens facing the optical disk to prevent collision of the objective lens and the optical disk. The shock absorber has a surface resistivity of not more than 1010 Ω at least for the projection. In this way, the shock absorber (projection) will not be electrified when the optical disk and the shock absorber (projection) collide with each other, and accordingly the shock absorber (projection, in particular) does not attract dust or particles. As a result, the dust or particles do not damage the optical disk even when the optical disk and the shock absorber (projection) collide again.