US Patent 10151919 Lens device

There is provided a lens device that prevents dust from entering a space in which a movable lens is moved. A movable lens is moved in the direction of an optical axis. A holding member, which extends in the direction of the optical axis, is formed at an end portion of the movable lens. A magnet is fixed to an end portion of the holding member. A hall IC is disposed in a closed storage space at a position facing the magnet. A signal, which corresponds to the position of the magnet in the direction of the optical axis, is output from the hall IC. Since the hall IC is disposed in the storage space closed by a storage box, the entry of dust, which is caused by the hall IC, into a space in which the movable lens is moved is prevented.