Patent ID: 7937722

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 an outer circumferential side of 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 a circumferential side of the claw portion and is a pivotal portion for a movement of the tip portion in, at least, axially downward direction, wherein the center case further includes a movement pivot receiving portion extending radially inwardly of the cylindrical portion, arranged opposite from the movement pivot portion, and receiving a movement of the movement pivot portion, wherein a support point extending continuously from the movement pivot portion is arranged radially inwardly of the movement pivot portion at the movement support portion, wherein axially upward movement of the tip portion is substantially prevented since the support point makes contact with the movement pivot receiving portion, and a top surface of the movement support portion makes contact with a bottom surface of the top plate portion, wherein the movement pivot receiving portion is arranged radially inwardly of the movement pivot portion when the tip portion is at an axially lowest point, and wherein the movement pivot receiving portion extends, when removing the disk from the chucking mechanism, radially inwardly of the support point while the claw member is at a radially innermost position.