Patent ID: 7035173

Claim:
An optical pickup apparatus for a recording medium having a light transmitting layer on which an information signal is recorded, comprising: a light source for emitting light; an objective lens for focusing the light emitted from the light source onto the recording medium; focusing driving means for moving the objective lens in a first direction which is parallel to an optical axis thereof; tracking driving means for driving the objective lens in a second direction which is perpendicular to the optical axis; a lens assembly disposed between the light source and the objective lens and having first and second lenses each of which is independently displaceable along an optical axis thereof; driving means, having separate driving elements corresponding to the respective lenses in the lens assembly, for displacing the corresponding lenses in the lens assembly independently of each other along the optical axis thereof in such a manner as to reduce a spherical aberration caused due to a thickness of the light transmitting layer and spherical aberrations which occur on optical surfaces of an optical system; a first voice coil provided on the objective lens and wound about the optical axis; a second voice coil provided on the first lens in the lens assembly and wound about the optical axis; a pair of permanent magnet pieces disposed outward of the first and second voice coils and magnetic poles oriented perpendicularly to the optical axis; said focusing driving means performing focusing by varying the current in said first voice coil; first driving means for performing positioning according to a type of the recording medium by feeding a current to the second voice coil; and second driving means for performing positioning according to a type of the recording medium by driving the second lens along the optical axis thereof.