Patent ID: 7602583

Claim:
A clamping device that fixes a disc onto a spindle motor that rotates the disc, said clamping device comprising: a clamp ring configured to cap the disc, the clamp ring having a plurality of concentrically arranged screw holes; and a plurality of screws each configured to be inserted into a corresponding one of the screw holes and to fix said clamp ring onto the spindle motor, each screw including a head, a shaft part including a threaded portion, and a neck located between the head and the shaft part, the head having a seating surface as a back surface configured to contact the clamp ring and to incline relative to a plane perpendicular to a central axis of the screw, the seating surface of said screw having an inclined angle greater than a plane that contacts the seating surface of said screw of said clamp ring before said clamp ring is fixed by said screw, and the neck being tapered from the seating surface to the shaft part so that the neck can incline relative to the plane perpendicular to the central axis of the screw at an angle greater than that of the seating surface.