Patent ID: 7489600
Filing Date: 2009-02-10
Classification: G11B

Abstract:
1. An object lens driving device, comprising: a movable unit that includes an object lens and an object lens holding member for holding the object lens; a plurality of elastic supporting rods which rods are arranged on two sides of the movable unit in a tangential direction and support the movable unit while allowing the movable unit to move relative to a fixed unit in a focusing direction and a tracking direction, said focusing direction being in an optical axial direction of the object lens, said tracking direction being perpendicular to the focusing direction; and a driving unit that includes a focusing thrust force generation unit configured to generate a thrust force to displace the movable unit in the focusing direction and a tracking thrust force generation unit configured to generate a thrust force to displace the movable unit in the tracking direction; wherein a moment M approximately expressed by formula ( where a is a coefficient, Xfo represents a magnitude of a focusing movement, Xtr represents a magnitude of a tracking movement, k θrepresents a tilt spring constant, kfo represents a spring constant in the focusing direction, and ktr represents a spring constant in the tracking direction.