Patent ID: 6757238
Filing Date: 2004-06-29
Classification: G11B

Abstract:
A disc clamping device comprising:a turntable on which a disc is placed and rotated by a driving source, an engagement body which is provided in a rotation center portion of the turntable, to which a center hole of the disc is passed through in an axial direction, a plurality of clamp bodies each of which is provided in such a manner that each clamp body is movable between a retracting position which is stored inside of the engagement body and an extending position which extends in a radial direction outward from an outer peripheral surface of the engagement body, each of the clamp bodies arranged such that there is a gap space between an underface of the clamp body and the turntable, such that the clamp body moves entirely downward, biasing means by which each of the clamp bodies is pushed outward in a radial direction from the inside of the engagement body for extending and pressing a tip operating portion of the clamp body against an upper part fringe angle portion of the center hole of the disc, wherein, when the center hole of the disc passes through the engagement body, each of the clamp bodies is depressed in an axial direction by abutting a lower fringe angle portion of the disc center hole against the upper surface of the tip operating portion of the clamp body and then pushed into the inside of the engagement body such that the disc is attained to be centering and passed through, when the disc is positioned in the fixed location, the under surface of the tip operating portion of the clamp body overlaps and presses from the upward side on the upper fringe angle portion of the disc center hole in the axial direction such that the disc is held by means of compulsion force of the clamp body, and an entry guide portion to guide centering of the disc center hole is provided in an upper limb portion in an axial direction in an outer circumferential surface of the engagement body, the entry guide portion being exposed when the clamp body moves downward, at least the tip operating portion of the clamp body is held so as to have an up and down motion in an axial direction, the tip operating portion moves down by force when the disc is depressed to expose the entry guide portion, when the disc is located in the fixed location, the tip operating portion is pushed up at the upward position by means of the reaction force of the compulsion force.