The present invention provides a thin film semiconductor element which is small in area with high on-current enough to be suitable for the power saving, miniaturization, and high definition display of a device. A second oscillating signal presenting an instantly transiting edge, which occurs simultaneously with either the peak or the valley of the first oscillating signal, is generated. The method then includes press-cutting a leading end of the base plate to form leading ends. Moreover, the corrective lens body can be rotated horizontally in relative to the surface of the lens of the diving mask for position adjustment and vision correction. The defined channel can engage an edge of the windshield of the automobile.