Patent ID: 7908614

Claim:
A chucking mechanism operable to detachably set thereon a discoid disk including a central opening portion, the chucking mechanism comprising: a center case arranged concentrically with a predetermined central axis, including a cylindrical portion which fits the central opening portion, a top plate covering an axially upper side of the cylindrical portion, and a plurality of openings arranged in a circumferential direction extending from the cylindrical portion to the top plate portion; a claw member movable with respect to the opening, protruding in a radially outward direction from the cylindrical portion, and making contact with the central opening portion of the disk; an elastic member providing radial force to the claw member; and a turn table including a disk setting surface setting thereon the disk, wherein the claw member includes a claw portion having a disk retaining surface making contact with the central opening portion and retaining the disk, and a movement support portion having a movement pivot portion which is arranged on circumferential side of the claw portion and is a pivotal portion for a movement of a tip portion in, at least, axially downward direction, and a movement assist portion which is arranged radially inwardly of the movement pivot portion and guides the claw member moving in the radially inward direction, the center case includes a movement pivot receiving portion receiving movement of the movement pivot portion, and a movement support receiving portion receiving movement of the movement assist portion, and the movement support receiving portion and the movement pivot receiving portion each are arranged radially inwardly of the cylindrical portion, wherein the center case is made by an injection molding and made of a resin material, the center case includes at least two movement pivot receiving portions arranged correspondingly to the openings circumferentially apart from one another, wherein the opening includes a widened portion whose circumferential width is greater than a rest of the opening, wherein the circumferential width of the widened portion is greater than a circumferential width of a pair of movement pivot receiving portions, and wherein the circumferential width of the widened portion is greater than a radial width of the movement pivot receiving portion.