An operation mechanism is provided, including a fixed ring and a rotating assembly, wherein the rotating assembly is rotatably connected to the fixed ring. The rotating assembly includes a rotating ring and a movable portion. The rotating ring connects to the fixed ring. The rotating ring and the movable portion are fixed to each other. The movable portion is disposed on a surface of the fixed ring and configured to contact a circuit board disposed on the surface. When the rotating assembly is rotated from a first position to a second position relative to the fixed ring, the movable portion moves from a first contact position to a second contact position relative to the circuit board.