US Patent 7408721 Zoom lens

A zoom lens includes a housing, a rotatable adjustment member, a spring member and a lens barrel. The rotatable adjustment member has a ring body rotatably coupled to an inner bottom surface of the housing in such a manner that the ring body is axially moveable relative to the housing when the ring body is rotated. The spring member is a non-planar ring member having two first opposite end portions stopped at an inner top surface of the housing, and two second opposite end portions stopped at a step of the ratable adjustment member. The lens barrel is disposed through an axial hole of the housing and connected to the rotatable adjustment member such that the lens barrel is synchronously movable with the rotatable adjustment member.