An apparatus includes a rotating body M assembled with a supporting body and rotating at least between a standard position and a deployed position. The rotating body at the deployed position is applied with a biasing force in a direction of returning the rotating body to the standard position. A speed switching device is provided to change a rotational speed of the rotating body from the deployed position to an intermediate position different from that from the intermediate position to the standard position in a return rotational movement of the rotating body.
