The present invention provides a power tool with a hand proximity detector to detect the hand of an operator and a trigger circuit operable with the detector to control the operation of a light in the housing or to provide a safety lockout function. In a first control time period based on the leading edge of the recording medium as a reference, a driving unit is controlled in accordance with detection of a loop. In an exemplary manner, the field information between a video portion of a main television signal and a video portion of an auxiliary output television signal is tracked for determining field inversion between the two. An inclined position of the material roll, arranged on the transfer table, is determined by sensors. In one embodiment, the spent treating solution is recycled to form a regenerated hypochlorite stream for use in the treatment solution. Therefore, if the vehicle has collided, the power supply is shut off immediately, and if the vehicle has not really collided, the power supply is not shut off so as to surely enable the vehicle to run.