A drive mechanism for driving a plurality of components arranged in a ring shape to move back and forth in a radial direction, the drive mechanism is disposed in an annular disk, each component has a shoulder, the drive mechanism includes: a circular body coaxial disposed on the annular disk; a drive wheel rotatably disposed coaxially with the circular body; a cam ring disposed coaxially with the drive wheel, having a diameter smaller than that of the drive wheel, and including at least one cam; a plurality of pushing elements provided for contacting the shoulder of the respective components and each having a driven portion abutted against the cam ring, so that the pushing elements are moved toward or away from the axis, and the pushing elements contact the shoulders to drive the components to move in the radial direction or in the direction of the axis.