An optical element includes a first microlens array unit and a second microlens array unit in each of which a plurality of microlenses are arranged. With the above configuration of the present invention, the presentation-related data of various applications running in the host can be redirected as demanded by a user to a corresponding presentation device. Because the incline of backrest frame is controlled by an adjusting wheel pushing the spring and because the seat frame has a rocking board to support the backrest frame, the chair assembly is able to change the inclined angles of the backrest frame. Then, the gear position of the transmission is moved to a lower position by one stage with the clutch being disconnected.