Patent ID: 8634147

Claim:
An apparatus that transfers an optical element, the apparatus comprising: a driving unit that generates a driving force in response to an external signal; an output shaft that rotates by the driving force of the driving unit; a rotating plate that is connected to the output shaft and rotates with the output shaft; a first deceleration unit that comprises first deceleration balls that contact the rotating plate, and a first deceleration plate that rotatably supports the first deceleration balls and is disposed to be rotatable with respect to the rotating plate; a rotating shaft that has an outer screw surface and that rotates with the first deceleration unit by being coupled to the first deceleration unit; an intermediate plate that is disposed to be rotatable with respect to the first deceleration plate and frictionally contacts the first deceleration balls; a second deceleration unit that comprises second deceleration balls that contact the intermediate plate, and a second deceleration plate that rotatably supports the second deceleration balls and that is disposed to be rotational with respect to the intermediate plate; a transmission unit that transmits an external rotational force to the second deceleration unit; and a moving unit that supports the optical element and that is engaged with the outer screw surface of the rotating shaft and moves with the rotating shaft as the rotating shaft rotates; wherein, in order for the intermediate plate to be maintained in a stopped state while the rotating plate rotates due to the driving unit, a driving force of the driving unit transmitted through the first deceleration unit to the intermediate plate is set to be smaller than a force necessary for rotating the transmission unit; and wherein, when the driving unit does not generate the driving force, the rotating shaft is in a state where the rotating shaft is rotatable due to the external force, and when the external rotational force is transmitted through the transmission unit to the second deceleration unit, the intermediate plate, the first deceleration unit, and the rotating plate rotate together due to the second deceleration unit.