The present invention discloses a Class-D power amplifier and control method thereof. A tripod member having a trunnion barrel adapted to be fitted to a shaft for torque transmission and trunnion journals radially projecting from three circumferentially equispaced positions in the trunnion barrel. The scaling structure includes: a multi-layer structure having a first layer formed above one of the substrates and a second layer formed above the first layer; an opening structure having a first opening in the first layer and a second opening in the second layer and formed at the multi-layer structure. The bushing is secured to the other of the door and the door jamb of the enclosure. When the difference is no less than the predetermined value, the lane detecting apparatus transfers to a car pool lane detection mode in which the candidate line selecting part detects the one or more candidate lines in accordance with a threshold that is less than the edge threshold.