The present invention relates to a power drill which comprises a spindle and a rear bearing mounted on the rear portion of the spindle. A light shielding film provided under an active layer of a pixel TFT and the pixel TFT, the active layer of the pixel TFT, and a thinned gate insulating film are used to form a gate wiring and a capacitor. When the button is released and shifted away from the first contact, a space will be provided for the first contact to return an original status prior to deformation. Because the compressor motor operates according to operational conditions of the fan motor, an overload can be prevented.